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- 2D transformationsTranslation, rotation, scaling, reflection and shear of a figure; the centre of a rotation; composing transformations and the order that matters.
- 3D and renderingMesh, normals, model, view and projection matrices, perspective, rasterisation, depth buffer, Lambert and Phong lighting, textures, ray tracing.
- Abstract classesThe abstract class in Java: not instantiable, abstract methods to override, shared concrete methods, a concrete or still abstract subclass, and the template method.
- Abstract data types and encapsulationThe abstract data type: its operations and their properties, interface versus implementation, constructors, accessors and modifiers, the invariant, and what encapsulation protects.
- Accounts and groupsUID and GID, the seven fields of /etc/passwd, the role of /etc/shadow and /etc/group, primary and secondary groups, people accounts and service accounts, and the id, whoami and groups commands.
- ACID transactionsBEGIN, COMMIT, ROLLBACK and SAVEPOINT, autocommit, the four ACID properties (atomicity, consistency, isolation, durability) and the log that upholds them.
- Active DirectoryLogical and physical structure, objects and group scopes, group policies and their order, Kerberos, the DNS dependency and operations master roles.
- Activity diagramThe notation of the UML activity diagram: initial and final nodes, actions, decision and merge with guards, fork and join, swimlanes.
- Adder and multiplexerThe usual combinational circuits: half adder, full adder, ripple-carry adder, multiplexer, demultiplexer, decoder and their place in the arithmetic logic unit.
- Administering an analytics schemaRunning an analytics schema in a relational DBMS: schema, roles and read rights, views and materialised views, indexes, partitioning of the fact table and evolving it without breaking reports.
- Advanced debuggingHunting a hard bug methodically: hypotheses, minimal reproducible example, git bisect, watchpoint, concurrent access, memory leak, thread and heap dumps.
- Advanced DHCPScopes, exclusions and reservations, the life of a lease, options, the relay agent between networks and redundancy with two servers.
- Advanced DNSThe zone and its file, the SOA and the serial number, transfer from primary to secondary, delegation and glue, the reverse zone and the difference between authoritative and recursive servers.
- Advanced Docker: hardening a container and keeping it aliveRemoving a container's unneeded privileges, keeping secrets out of the image, capping its resources, monitoring it with a HEALTHCHECK and choosing its restart policy.
- Advanced Docker: lean imagesBuilding in several stages, choosing a minimal base image, ordering layers to benefit from the cache, excluding what has no place in the image, pulling by digest and pushing to a private registry.
- Advanced JavaScript: classes, modules and modern syntaxThe prototype and the prototype chain, class, extends and super, modules with import and export, destructuring, spread and optional chaining.
- Advanced JavaScript: scope, closures and thisLexical scope and the scope chain, the closure that keeps its variables, the value of this depending on how the function is called, and the this lost inside a callback.
- AESThe AES parameters, the 4 × 4 state, the four operations of a round, the last round without MixColumns, and what sets AES apart from DES.
- Aggregate functionsSumming up a whole table into a single value: COUNT (star, column, DISTINCT), SUM, AVG, MIN, MAX, how NULL is treated and the ban on mixing an aggregate with a plain column.
- Algebra for imagingThe matrices that transform: products, rotation, scaling and shear matrices, homogeneous coordinates for translation, composing in the right order, inverses and change of frame.
- Alphabets, words, languagesThe vocabulary of formal languages: alphabet, word, empty word, length, concatenation, power, mirror, prefix, suffix, factor, language, Σ* and the Kleene star, with computations on finite languages.
- ALTER and DROPChanging a schema: ALTER TABLE (add, remove, rename a column, change a type, add or remove a constraint), DROP TABLE with RESTRICT or CASCADE, and the difference between DROP, TRUNCATE and DELETE.
- Alternatives, contrast and keyboardThree accessibility requirements: a text alternative suited to an image's role, text contrast (4.5:1 and 3:1) and keyboard navigation (tab order, visible focus, skip link, keyboard trap).
- Analysing a frame captureDecoding a frame layer by layer, reading Wireshark's three panes, telling a capture filter from a display filter, and drawing conclusions from a capture.
- Analysing loops and recurrencesGoing from code to its cost by calculation: number of iterations of dependent loops, the recurrence of a recursive algorithm, the recursion tree, the master theorem and amortised cost.
- Analysis tools: pandas and scikit-learnThe toolkit of a Python analysis: Jupyter notebook, NumPy and pandas for tables, scikit-learn and its fit, transform, predict, score contract, splitting the set, the pipeline; R, Orange and KNIME only situated.
- Analytic geometry for imagingPoints and vectors, dot and cross products, lines and planes, ray intersection and linear interpolation: the calculations behind lighting, rendering and gradients.
- Anatomy of a unit testWhat a JUnit unit test is made of: the test class, the @Test annotation, the fixture, the Arrange-Act-Assert plan, one test per behaviour, independent tests and a name that says what is checked.
- AntivirusThe four detection methods (signature, heuristic, behavioural, sandbox), quarantine, false positives and false negatives, updating the databases, an antivirus's limits and what an EDR adds.
- API stylesREST, GraphQL, gRPC and webhooks: what each does, when to choose it, and the rules that avoid duplicates, broken clients and inconsistent lists.
- ARIA rolesLandmark and component roles, ARIA properties and states (aria-label, aria-labelledby, aria-expanded, aria-hidden, aria-live), accessible name, and the first rule: a native element before ARIA.
- ARPThe broadcast ARP request and the direct reply, the ARP cache, ARP towards the gateway for an outside destination, gratuitous ARP and reading the cache with ip neigh.
- ASCII, Unicode and UTF-87-bit ASCII, Latin-1, Unicode and its code points, UTF-8 from 1 to 4 bytes, UTF-16 and UTF-32 for comparison, the byte order mark and wrongly decoded text.
- Assembly and addressing modesReading an ARM assembly program, its labels, mnemonics and directives, recognising the five addressing modes and translating a condition or a loop into comparisons and jumps.
- Assertions and preconditionsStating what a function assumes and what it guarantees: precondition, postcondition, invariant, the assert statement and its failure, defensive programming, and the difference with checking an input.
- Association, aggregation, compositionThe three links between objects: association, aggregation and composition. Recognising each one in a statement or in Java code, setting multiplicities and navigability, and translating a link into attributes.
- Asynchronous requests in JavaScriptfetch, promises (then, catch, finally), async and await, the execution order of asynchronous code and the handling of network and HTTP errors.
- Attributes and methodsThe class as a mould and the object as an instance: attributes, methods, creation with new, dot notation, this and the state each object keeps for itself, in Java.
- AuthenticationKnowing who the user is and what they may do: sessions and cookies, JWT, OAuth and OpenID Connect, passwords, and the most common flaws.
- Automating administrationWhy automate, imperative script versus described state, idempotence, pushing without an agent or pulling with one, and Ansible: inventory, playbook, tasks, modules, variables, handlers and reading a run.
- Automating your testsRunning the whole test suite with a single command and reading the result: build tool, report (run, failures, errors, skipped), exit code, running a single class or test.
- Automaton minimizationMaking a complete deterministic automaton as small as possible: unreachable states, equivalent states, separating word, Moore's partition refinement, quotient automaton and uniqueness of the minimal automaton.
- AvailabilityWhat the “nines” of availability mean, how redundancy raises it and why a single point of failure brings it down. Simple calculations, scenarios and failures, every answer explained.
- AZ-104AZ-104 Review – Microsoft Azure AdministratorThe natural next step after AZ-900: identities, storage, compute, networking and monitoring, seen from the administrator who works hands-on in Azure. Cards written from the official skills outline in effect since April 17, 2026. Voyelle is not affiliated with Microsoft. AZ-104 and Microsoft Azure are trademarks of their respective owners.
- AZ-900AZ-900 Review – Microsoft Azure FundamentalsThe fundamentals of cloud computing and Azure, one card at a time: cloud concepts, Azure architecture and services, and Azure management and governance. Built on the official exam skills outline as of July 20, 2026. Voyelle is not affiliated with Microsoft. AZ-900 and Microsoft Azure are trademarks of their respective owners.
- Backing up and restoring a databaseSaving and recovering a PostgreSQL database: logical or physical backup, full, differential, incremental, WAL, point-in-time recovery, loss and downtime targets, the 3-2-1 rule.
- BackupsFull, incremental and differential backups, the chain to restore, the 3-2-1 rule, acceptable data loss and downtime, retention, an offline copy against ransomware and the restore test.
- Balanced treesThree trees that keep a logarithmic height: the AVL tree (balance factor, single and double rotations), the red-black tree (its properties) and the B-tree (order, full node, splitting).
- Bases 2, 8 and 16Positional notation and conversions of natural numbers between decimal, binary, octal and hexadecimal: successive divisions, sum of weights, grouping by 3 and 4 bits, the 0b, 0o and 0x prefixes.
- Bash: functions and arraysDeclaring and calling a function, variable scope with local, return versus echo, indexed and associative arrays and reading options with getopts: predicting what a script prints.
- Bash: quoting and expansionsThe order of shell expansions, the three kinds of quoting, word splitting, the ${v:-d}, ${v%m} and ${v##m} forms and the here-document: predicting the arguments a command receives.
- Bastien and Scapin's 8 criteriaBastien and Scapin's 8 ergonomic criteria and their 18 elementary criteria: recognising which criterion an interface flaw breaks and what each one asks for.
- Battery lifeWhat drains a phone's battery, the limits the system puts on background work, the wake lock, batching and deferring tasks, and choosing the accuracy and frequency of location updates.
- Behaviour-driven developmentBehaviour-driven development: three amigos workshop, example mapping, Gherkin scenarios tied to code by step definitions (Cucumber), declarative style and living documentation.
- Behavioural patternsThe eleven behavioural patterns of the GoF catalogue: Chain of Responsibility, Command, Interpreter, Iterator, Mediator, Memento, Observer, State, Strategy, Template Method and Visitor. Intent, participants and code examples.
- Best, worst and average caseThe cost of an algorithm depends on the input, not only on its size: best case, worst case and average case, for the searches and sorts of the path.
- BGPAutonomous systems and their numbers, interior against exterior routing, eBGP and iBGP sessions over TCP 179 and their four messages, path vector and AS_PATH, best-route choice in short form, route hijacking and leaks.
- Big O notationThe O, Ω and Θ notations, their definition by a constant and a threshold, the rules for simplifying a cost and the scale of growth classes, from 1 to n!.
- Binary arithmetic and overflowAddition and subtraction on n bits, subtraction through two's complement, shifts, carry and overflow flags, and what an overflow does in a real program.
- Binary searchSearching a sorted array by halving the interval: left and right bounds, middle, the half kept, stopping condition, bound updates and the maximum number of steps.
- Bits, bytes, kB and KiBBit, nibble, byte and word; how many values n bits can code; decimal against binary prefixes; rates in bit/s against sizes in bytes; orders of magnitude of common sizes.
- BlockchainThe block and its header, the chain of digests, the Merkle tree and the inclusion proof, proof of work and its difficulty, the longest-chain rule, double spending and proof of stake.
- Boyce-Codd normal formBoyce-Codd normal form: every determinant is a superkey; the case of a 3NF relation that does not meet it, the decomposition, and its price: a dependency that no table enforces any more.
- Branching strategiesHow a team organises its Git branches: Git Flow with its five kinds of branches, GitHub Flow and its short branches, trunk-based development; where each branch starts and returns, and which strategy to choose.
- Breakpoints and steppingDriving a debugger: plain and conditional breakpoints, step over, step into and step out, resume, the variables and call stack views, watch expressions.
- Bubble sortSorting by comparing neighbours and swapping them, pass after pass: the largest value rises, the inner loop bound shrinks, and a pass with no swap lets you stop.
- Building a model into an applicationCalling a model from your code: the request (system role, messages, temperature, token limit), the response and its cost, structured output, tool calling, retrieval-augmented generation, the key kept on the server, prompt injection, timeouts and retries.
- Building a replicated clusterReplication on the administrator's side: a standby by streaming replication, synchronous or asynchronous mode, lag monitoring, failover, split brain, quorum, witness and replication slots.
- Building a REST serviceDesigning a REST service: resources and URIs, the meaning of each HTTP method, response codes, statelessness, safe and idempotent methods.
- CachingKeeping data close so it need not be recomputed: cache-aside, write-through, time to live, eviction, invalidation, and what happens when the cache empties or fails.
- Cartesian product and divisionThe Cartesian product (schema, number of tuples, link with the join) and relational division, which answers questions of the “those associated with all” kind: computing it and recognising the question that calls for it.
- Cellular automataGrid, states, neighbourhood and a local rule applied everywhere at once; elementary automata and the Wolfram number; Conway's Game of Life and its patterns.
- Centralising monitoringThe monitoring server and its probes: collection by polling or by pushing, SNMP, the four states of a service and confirmation, dependencies between hosts, escalation, Prometheus and its exporters, and who watches the monitor.
- Certificates and public key infrastructureThe X.509 certificate field by field, the leaf, intermediate and root chain, the roles in a public key infrastructure, the life cycle (request, issuance, renewal, revocation) and the most common certificate errors.
- Character stringsThe string as an indexed sequence of characters: length, access, slicing, concatenation, immutability, traversal, lexicographic order and common operations (case, search, replacement, splitting, joining).
- Checked and unchecked exceptionsJava's Throwable hierarchy (Error, Exception, RuntimeException), the catch-or-declare rule, the throws clause and the choice of type when you write your own exception.
- Choosing a chartFive intentions (compare, trend, composition, distribution, relationship) and the chart for each, how precisely visual encodings can be read, and four traps: truncated axis, dual axis, 3D effect, too many categories.
- Choosing a data structureThe cost table of the path's data structures and the method that starts from the most frequent operations: diagnosing a slowdown, matching a need to a structure and reading the cost of an operation.
- Class diagramThe notation of the UML class diagram: the three-compartment box, visibilities, static and abstract members, multiplicities and the five links (generalisation, realisation, aggregation, composition, dependency).
- CLF-C02AWS Cloud Practitioner Review (CLF-C02)Everything you need to pass the Cloud Practitioner: cloud concepts, security and compliance, core services, and billing and support. Built on the official CLF-C02 exam guide. Voyelle is not affiliated with Amazon Web Services. AWS and CLF-C02 are trademarks of their respective owners.
- Cloning, backing up, restoringWhat sets a clone, a template, a snapshot and a backup apart for a virtual machine, then, for containers, what is rebuilt and what is backed up, down to the verified restore.
- Code audit toolsThe families of tools (linter, static analyser, profiler, coverage analyser, dependency analyser), static versus dynamic analysis, reading a report and the quality gate that blocks a delivery.
- Code coverageMeasuring what the tests execute: statement, branch, condition and path coverage, reading a coverage rate, and why 100% does not prove the code is right.
- Code documentationDocumenting code for whoever takes it over: Javadoc comments and their tags, comments that say why, the README, generated documentation.
- Code metricsThe static measures of a piece of code and their usual thresholds: lines of code, cyclomatic complexity, cognitive complexity, coupling, cohesion, duplication, technical debt, and what a metric does not tell you.
- Code review for efficiencyReading someone else's code with cost in mind: the six-point checklist, the level of a remark (blocking, suggestion, taste) and how to word it.
- Code smellsThe smells Fowler describes, which say a piece of code deserves rework, grouped into families (bloaters, object-orientation abusers, change preventers, dispensables, couplers), plus magic numbers; recognising them in a snippet and behind a symptom met in practice.
- Collecting big data and its file formatsWhere big data comes from and how it is stored: the three Vs, batch or stream collection, API pagination, and six file formats (CSV, JSON Lines, XML, Avro, Parquet, ORC) compared.
- Colour scienceAdditive and subtractive mixing, the RGB, CMYK and hue-saturation-lightness models, hexadecimal colour codes, luminance and greyscale, gamut.
- Comparing and sorting objectsGiving objects an order: natural ordering with compareTo and the sign of its result, the external comparator, successive criteria, sorting a collection and consistency with equality.
- Compile-time, run-time and logic errorsThe three families of errors in a Java program: what the compiler refuses, what crashes at run time and what runs but gives a wrong result, including how to read a real javac message.
- Complex architecture patternsSeven patterns, each with the problem it solves, its price and when to do without it: microservices, API gateway, event-driven architecture, CQRS, event sourcing, saga and circuit breaker.
- Complexity classesThe classes P, NP, NP-complete and NP-hard, checking a certificate, polynomial reduction, the reference problems (SAT, knapsack, travelling salesman, colouring) and the size each cost lets you handle in a given time.
- Computing in Z/nZResidue classes modulo n, addition and multiplication, invertible elements and zero divisors, the inverse by the extended Euclidean algorithm, and solving ax ≡ b modulo n.
- Conditions: if, else, else ifRunning one block or another depending on a condition: if, if-else, else-if chains, nested tests and multi-way selection, with the logic errors that come up most.
- Configuration filesWhere a system's and a user's settings live, the common formats (key=value, INI, YAML, JSON), the priority order of the sources and the need to reload the service.
- Configuring a firewallnftables tables, chains and hooks, default policy, connection tracking, address translation and port forwarding, logging, and the safe order of a ruleset.
- Configuring a routerThe command line of a Cisco IOS router: the modes and their prompts, configuring an interface, writing a route, running and startup configuration, and reading show commands.
- Connections and prepared statementsReaching a database from a program: driver, connection string, the open, prepare, bind, execute, read, close cycle; prepared statements against concatenation, SQL injection and releasing resources.
- Console input and outputReading from the keyboard, printing, converting an input, formatting an output (separator, line ending, number of decimals) and checking an input with a loop.
- Constraints in SQLPRIMARY KEY, FOREIGN KEY and REFERENCES, UNIQUE, NOT NULL, CHECK, column and table constraints, named constraints, and the ON DELETE and ON UPDATE actions (RESTRICT, CASCADE, SET NULL).
- ConstructorsInitialising an object's state when it is created: default constructor, parameterised and overloaded constructors, this(…) calls, attribute default values and copy constructors, in Java.
- Consuming a web serviceCalling a web service from a program: asynchronous call, promise, reading the response, HTTP errors, timeouts, authentication token, pagination.
- Container versus virtual machineWhat each one carries and shares, the comparison on seven criteria (kernel, isolation, weight, start-up, density, portability, guest system) and the constraints that decide between them.
- Containers in the pipelineRunning a job in an image, adding services to it, building, tagging and pushing the image, telling a tag from a digest, promoting the same image from one environment to the next and scanning it.
- Continuity and recovery plansThe continuity plan against the recovery plan, the impact analysis, the maximum tolerable downtime and data loss, the four kinds of standby site, the steps of a recovery, failover and the return to normal.
- Continuous delivery and deploymentEnvironments and the promotion of one artifact, continuous delivery versus continuous deployment, per-environment configuration, compatible database migrations, rollback and the four DORA metrics.
- Continuous inspectionStatic analysis run on every push: linter, SonarQube's finding families, coverage and duplication measures, technical debt, ratings, a quality gate on new code and false positives.
- Continuous integration and deliveryIntegrating and delivering continuously: a build and tests on every push, fast feedback, a main branch that is always releasable, pipeline stages, the artifact, and the difference between continuous delivery and continuous deployment.
- Continuous integration: the server and its runnersHow a continuous integration server such as GitLab CI or GitHub Actions works: triggers, runners, cache and artifacts, masked secrets, reproducible builds and protected branches.
- Counting operationsCounting the elementary operations of a piece of code as a function of the size n: a simple loop, successive loops, nested loops, a dependent loop and a loop that halves.
- Coupling and cohesionMeasuring and judging dependencies: the kinds of coupling between modules, afferent and efferent coupling, instability, and the levels of cohesion inside a module, from coincidental to functional.
- CREATE TABLE and data typesThe CREATE TABLE statement and the usual column types (INTEGER, NUMERIC, VARCHAR, CHAR, DATE, TIMESTAMP, BOOLEAN), the DEFAULT clause: choosing a type and predicting what the database stores, transforms or rejects.
- Creating and removing usersThe useradd and adduser commands, passwd, usermod with -aG, -s and -L, userdel with -r, groupadd and groupdel, the /etc/skel template and the home directory.
- Creational patternsThe five creational patterns of the GoF catalogue: Singleton, Factory Method, Abstract Factory, Builder and Prototype. Their intent, participants, a code example and their limits.
- Critical section and mutexThe critical section and mutual exclusion, what a correct solution must guarantee, the atomic operation, the POSIX mutex (lock, unlock, trylock), busy waiting versus blocking and lock granularity.
- CSRF vulnerabilitiesMaking the victim's browser send a request she did not intend: the conditions, the defences (anti-CSRF token, SameSite, origin check) and why a GET must change nothing.
- CSS positioningThe five position values (static, relative, absolute, fixed, sticky), the reference element of a positioned box, top/right/bottom/left and stacking order with z-index.
- CSS selectors and specificityTargeting elements with type, class, id and attribute selectors, pseudo-classes and combinators, then computing the specificity that settles a conflict between two rules.
- CSS units and coloursAbsolute and relative units (px, em, rem, %, vw, vh) and colour notations (hexadecimal, rgb, hsl, transparency): knowing what each value refers to and converting it.
- CursorsThe explicit cursor and its cycle (declare, open, fetch a row, test for the end, close), the FOR loop over a query, the parameterised cursor, the current row and row-by-row against set-based processing.
- Cyclic groups and modular exponentiationThe group of invertibles of Z/pZ, the order of an element, generators, Fermat's little theorem, Euler's theorem, Euler's totient and fast exponentiation.
- Data access: DAO, ORM, directoriesIsolating data access behind a dedicated layer: the DAO pattern, object-relational mapping, lazy loading and the N+1 problem, the LDAP directory.
- Data bindingObservable property, one-way and two-way binding, computed binding, converter, observable list, and the ban on writing into a bound property, using JavaFX properties.
- Data cleaningSix defects of a dataset (missing values, duplicates, outliers, inconsistent formats, wrong types, inconsistent columns) and how to treat them, keeping a trace of what was changed.
- Data consistencyWhen data is copied across machines, who sees what, and when? Strong consistency, eventual consistency, the CAP theorem, quorums and reading your own writes, as definitions and scenarios, every answer explained.
- Data redundancyWhy a flat table that repeats the same information contradicts itself, loses facts or refuses to record them, and how to split it into two tables so that each fact is written only once.
- Database accounts: who gets in, and howAdministering access to a PostgreSQL instance: login and group roles, inheritance of privileges, pg_hba.conf rules read top to bottom, expiry, connection limits and least privilege.
- Database federationQuerying several heterogeneous databases as one without copying their data: global schema, mediator, adapters and foreign tables, query splitting, filters pushed to the source, and what sets federation apart from a warehouse.
- Database federationQuerying several databases as one: remote server, user mapping, foreign table, what runs remotely or locally, two-phase commit, federating or copying into a warehouse.
- Datalog: recursion and negationRecursive rules, evaluation up to the fixed point, safe rules, stratified negation and the SQL equivalent with WITH RECURSIVE.
- DeadlockDeadlock and Coffman's four conditions, the allocation graph, prevention through a lock order, avoidance through the banker's algorithm, and how it differs from starvation and livelock.
- Decision trees and random forestsA classifier that asks threshold questions: reading a tree, measuring impurity (Gini, entropy), choosing the best split, bounding the depth; then the random forest, which makes bootstrapped trees vote.
- DenormalisationDeliberately stepping back from normalisation to read faster: copied column, precomputed counter, materialised view; what each technique costs in writes and consistency, and how copies are kept up to date.
- Dependency injectionGiving an object its dependencies instead of letting it create them: constructor and setter injection, the role of the assembler or container, and the effect on tests.
- Dependency managementDeclaring and controlling a project's libraries: manager, declaration file, semantic versioning, version constraints, transitive dependencies, scopes, lockfile and version conflicts.
- Deployment modelsPublic, private, community, hybrid and multicloud, compared on cost, control, compliance, elasticity and reversibility; regions, availability zones, data sovereignty and vendor lock-in.
- Deployment strategiesRecreate, rolling, blue-green, canary and feature flags: what each costs, what it guarantees, and why two versions living together must be compatible.
- Derivations and parse treesDeriving a word from the start symbol, leftmost and rightmost derivations, parse trees, ambiguous grammars and removing ambiguity with precedence levels.
- DESThe Feistel scheme and the DES cipher: blocks, key and rounds, the round function and S-boxes, decryption with the subkeys in reverse order, the weakness of the key, triple DES and the meet-in-the-middle attack.
- Designing a service end to endThree step-by-step designs, as in a system design interview: a URL shortener, a news feed, a messenger. For each: requirements, worked back-of-the-envelope numbers, the API, storage, scaling and failures, with the reasoning on the back.
- Designing an application protocolThe parts of a protocol: roles, messages and reply codes, text or binary format, message framing, the session state machine, errors, timeouts and version, with HTTP/1.1 and SMTP as examples.
- Deterministic finite automataThe deterministic finite automaton: states, transitions, initial state and accepting states, transition table, reading a word, recognized language, complete automaton with a sink state and the complement automaton.
- DHCP and joining a networkWhat happens when a device connects: DHCP and its four messages, the lease, reservation, relay, then ARP and DNS before the first page.
- Diffie-HellmanThe Diffie-Hellman key exchange: public parameters, exchanged values, the shared secret, what an eavesdropper sees, the discrete logarithm that protects the exchange, and the man-in-the-middle attack.
- Digital signaturesSigning and verifying: hash, then transform the digest with the private key, verify with the public key; what a signature guarantees and what it does not; RSA signing on small numbers; signing is not encrypting.
- Dimensionality reduction: principal component analysisSummarising many variables in a few axes: the curse of dimensionality, then PCA (variance, eigenvalues, scree plot, correlation circle, factorial plane); t-SNE and UMAP are only named.
- Distributed mining: MapReduce and SparkHow mining is computed across machines: map, shuffle, reduce, combiner and partitions, then Spark (lazy narrow or wide transformations, and actions) and the five mining tasks.
- DNSThe Internet's directory: resolvers, root and authoritative servers, record types, TTL and caching, and what happens when DNS goes down or an address changes.
- Docker ComposeThe compose.yaml file and its keys (services, image, build, ports, environment, volumes, depends_on, networks, restart, healthcheck), the default network and name resolution by service name, the up, down, ps, logs and exec commands.
- Docker: images and containersImage, container, registry, tag and daemon; the commands pull, run (-d, -p, -e, --name, --rm), ps, stop, start, rm, logs, exec, images and rmi; container states and port publishing.
- Document databasesThe document model on MongoDB: JSON document, collection, identifier, nested fields, flexible schema and validation, and the choice between embedding and referencing.
- DocumentationCommenting and documenting your code: the comment that adds something or merely paraphrases, a function's header (role, parameters, returned value, preconditions) and documentation that stays in step with the code.
- Documentation and user trainingWhat is delivered with the software so people can use it and run it: documentation types, the four genres (tutorial, how-to guide, reference, explanation), release notes and training plan.
- DRY, KISS, YAGNIThree rules of restraint in code: do not repeat the same knowledge (DRY), prefer the simplest solution (KISS), do not build what is not needed yet (YAGNI), and their limits.
- Dynamic array and linked listTwo ways to store a sequence: the array that doubles its capacity when full and the linked list. For each, the cost of access, insertion and deletion at the head, in the middle and at the end, amortised cost included.
- E-mail: SMTP, IMAP, SPF, DKIM and DMARCAn e-mail's journey, from submission to the inbox, and why it lands in spam: SMTP, MX, IMAP, and authentication with SPF, DKIM and DMARC.
- EBIOS and MehariThe five workshops of EBIOS Risk Manager and what each produces, the method's vocabulary (business value, supporting asset, risk source, targeted objective, feared event), then Mehari and what sets it apart.
- Eco-design in codeThe developer's levers for lean code, in four groups (processing, data, network, display), what gets measured and the guidelines that help.
- ElGamalElGamal encryption: public key and secret, encryption with a one-time random value, the pair (c1, c2), decryption through the inverse of the mask, and the danger of reusing the random value.
- EncapsulationThe four data units (data, segment, packet, frame), the header each layer adds when sending and removes when receiving, and what each device reads and rewrites along the path of a web request.
- Encapsulation and visibilityHiding an object's state: private, public, protected and package visibility, accessors and mutators, an invariant enforced by the mutator, and an internal reference not to hand out, in Java.
- Encrypting trafficSymmetric, asymmetric and hybrid encryption seen through use; in transit, at rest, end to end; pairs of plain-text and encrypted protocols; the VPN tunnel.
- Entities, attributes, identifiersThe building blocks of a data model: the entity and its occurrences, attributes (simple, composite, calculated), the identifier and the data dictionary. Relationships come in the next deck.
- Environment variablesShell or environment variable, export, env and printenv, PATH, HOME, USER, PWD, SHELL, LANG, inheritance by child processes, ~/.bashrc and which.
- Equivalence classes and boundary valuesChoosing test data without testing everything: splitting the inputs into valid and invalid equivalence classes, then aiming at the values at each class's boundaries, just before, on and just after.
- Error-correcting codesLinear block codes: length, dimension, minimum distance and rate, detection and correction power, encoding with a generator matrix, syndrome decoding and the families in use.
- Error-detecting codes: parity and CRCDetecting a transmission error: the parity bit and what it lets through, then the cyclic redundancy check, from the generator polynomial to the remainder of the modulo-2 division appended to the frame.
- Ethernet, MAC addresses and framesThe Ethernet II frame field by field, the 48-bit MAC address and its three kinds (unicast, multicast, broadcast), error checking, CSMA/CD and duplex.
- Evaluating a modelSaying what a model is worth on data it has not seen: train-test split, cross-validation, confusion matrix, accuracy, precision, recall, F1, ROC curve, and for regression MAE, RMSE and R².
- Exceptions inside the databaseThe EXCEPTION section of a block: predefined exceptions, RAISE, OTHERS, propagation from block to block, and what the error cancels in the transaction.
- Exchange formats: JSON, XML, CSV, YAMLThe formats used to exchange data between programs: serialisation, the six JSON types, XML elements and attributes, CSV, YAML; reading a parser error message and picking the right format.
- Exploring a massive datasetThe fixed plan of a first exploration: dimensions and types, per-column profile, sampling, group aggregates and a trend that reverses across subgroups.
- Extract, transform, load (ETL)The pipeline that feeds a warehouse: the three steps and the staging area, full or incremental loads, dimensions before facts, surrogate keys, slowly changing dimensions, replayable loads and the ELT variant.
- Facts, measures and dimensionsThe vocabulary of dimensional modelling: fact, grain, measure and its additivity, dimension, attribute, hierarchy, time dimension, degenerate dimension, and the four design steps.
- Feasibility criteriaThe feasibility study of a software project along five criteria, return on investment, payback period, the weighted decision matrix and the decision to go or not.
- File commandspwd, cd, ls, tree, mkdir, rmdir, touch, cp, mv, rm and find with their common options: what each one does, what it refuses and what it destroys.
- File shares: NFS and SMBWhat a mounted share is, NFS (exports, mounting, UID mapping, port 2049), SMB (the \\server\share name, per-user authentication, port 445), mounting from a host and its fstab line, and the effective permission.
- File system callsSystem call and library function, open and its flags, read, write, lseek, close, descriptors 0, 1 and 2, the return value, errno and perror.
- File types, inodes and linksThe seven file types shown by ls -l, what an inode holds, the directory as a table of names, hard and symbolic links, the link count, and the failures that follow from them.
- First, second and third normal formsThe first three normal forms in order: atomic attributes, no partial dependency, no transitive dependency; diagnosing a relation and decomposing it into 3NF.
- Fitts's law, Hick's law and the Gestalt lawsFitts's law (reaching a target), Hick's law (choosing among n options) and six Gestalt laws (how the eye groups things), applied to layout choices.
- FlexboxThe flex container and its children: main axis and cross axis, justify-content, align-items, gap, and how free space is shared with flex-grow, flex-shrink and flex-basis.
- Foreground and backgroundA shell's job control: launching with &, stopping with Ctrl+Z, jobs, fg, bg, the %n job numbers, the Running, Stopped and Done states, and surviving a terminal closing with nohup and disown.
- fork, exec and waitCreating a process with fork, making it run another program with exec, waiting for it with wait and its status, and knowing what becomes of orphans and zombies: predicting what each process prints.
- Form validationValidating on the client for comfort and on the server for security, validation rules, sending the form back with its errors and values, and redirecting after a successful submission.
- Forms and reportsThe data entry form bound to a table (controls, list fed by a foreign key, subform, validation) and the printable report (headers, detail, groupings, subtotals, footers).
- Frequency analysisLetter frequencies in French, a cryptogram's histogram, breaking a Caesar by its peak, the index of coincidence and why Vigenère flattens the histogram.
- Frequent pattern miningFinding what goes together in transactions: itemset, support, association rule, confidence, lift, and the Apriori algorithm with its pruning by the minimum support.
- From diagram to codeTurning a class diagram into Java code: visibilities, attributes, an association becoming an attribute or a collection depending on the multiplicity, navigability, generalisation, realisation and composition.
- From sketch to prototypeThe four artefacts: sketch, wireframe, graphic mock-up, interactive prototype; low and high fidelity; paper prototype; what each lets you test.
- From source to executableA C program's build chain: preprocessor, compilation, assembly, linking and loading, the .c, .h, .i, .s and .o files, static and dynamic libraries, gcc's -E, -S, -c, -o and -l options, and the difference between compiled, interpreted and virtual machine.
- From the conceptual model to the relational modelThe rules that turn a conceptual model into a relational schema: entity into table, identifier into primary key, relationship into a foreign key or a junction table, and the cases of attribute-carrying, reflexive and ternary relationships.
- Front-end framework: componentsSplitting an interface into a component tree, passing data down through props and events up, composing components, rendering a list with a key per item.
- Front-end framework: routingThe route table of a single-page application: path to component, parameters, nested routes, not-found page, navigation through the History API, access guard and lazy loading.
- Front-end framework: stateA component's local state and the render that follows, derived state, lifting state to the common ancestor, the shared store, and updating without changing in place.
- FTP and SFTPFTP and its two connections, active and passive modes, the commands and the reply-code families, the clear-text password; FTPS, and SFTP which goes through SSH on a single connection.
- Functional and non-functional requirementsTelling apart what the system does, how well it does it and the constraints placed on it, then writing a measurable requirement and prioritising it with MoSCoW.
- Functional dependenciesThe functional dependency X → Y, what data can refute, Armstrong's axioms, the closure of a set of attributes, the superkeys and candidate keys it gives, and the minimal cover.
- Functional testsBlack-box testing of what the specification promises: test cases, decision table, traceability matrix, acceptance test plan and acceptance testing.
- Functions and CASEThe usual scalar functions (strings, numbers, dates, CAST) and the CASE expression, simple or searched, including inside an aggregate: predicting what each expression returns, NULL included.
- Functions, parameters and scopeDefining and calling a function, passing it arguments, getting its return value, and knowing where a variable exists: local, global, shadowed.
- Garbage collectorAutomatic memory release: object reachable from the roots, reclaimable object, mark and sweep, reference counting and cycles, leaks through a reference kept by accident.
- Generic risksThe six families of risk for a system in operation, probability, severity and the criticality matrix, the four ways to treat a risk, the single point of failure, MTBF and MTTR.
- GenericsParameterised types: a collection of a given type, generic classes and methods, type checking at compile time, wrapper types and the bound of a type parameter.
- Git: branches and mergesA branch is a movable label on a commit: creating and switching branches, attached or detached HEAD, fast-forward merge or merge commit, deleting a merged branch.
- Git: rebase or mergeTwo ways to integrate a branch: merge, which keeps the history faithful with a merge commit, and rebase, which replays commits for a linear history; the golden rule, interactive rebase, squash and pull --rebase.
- Git: repository, index, commitGit's model: working directory, index and repository, what a commit contains, the hash that identifies it, HEAD and the four states of a file.
- Git: resolving a conflictWhen Git cannot merge on its own: the same lines changed on both sides, conflict markers, resolving, staging, concluding the merge or abandoning it with merge --abort.
- Git: the basic commandsThe everyday local commands, status, add, commit, diff, restore and log: what each one reads or changes in the working directory, the index and the repository.
- Git: the remote repositoryWorking with a remote repository: clone, origin, remote-tracking branches such as origin/main, fetch, pull, push and the rejection of a push that is behind.
- Good practiceThe eight measures of security hygiene: updates, least privilege, passwords and two-factor authentication, hardening, logging, backup, encryption of portable devices and phishing awareness.
- Grammars and the Chomsky hierarchyTerminals, non-terminals, start symbol and production rules; the language a grammar generates; the four Chomsky types with the shape of their rules, their machine and a witness language.
- GRANT and REVOKEGiving and taking away privileges (SELECT, INSERT, UPDATE, DELETE, ALL) on a table or on columns, from a role or from PUBLIC, WITH GRANT OPTION and REVOKE with CASCADE.
- Graph databasesThe property graph: nodes, directed and typed relationships, labels, properties; modelling a domain as a graph, walking from neighbour to neighbour without joins, and the typical uses.
- GridThe grid container (columns, rows, the fr unit, repeat, gap, named areas) and how children are placed (grid-column, grid-row, span): reading a grid, computing its columns and choosing between grid and flexbox.
- GROUP BY and HAVINGGrouping rows and computing an aggregate per group with GROUP BY, filtering groups with HAVING rather than WHERE, and knowing the order in which the database evaluates the clauses.
- Hash functionsA message's digest, the three resistances (preimage, second preimage, collisions), the avalanche effect, the birthday paradox and digest size, broken and recommended functions, file integrity and HMAC.
- HeapsortBuilding a max-heap in the array itself, then swapping the root with the last cell and sifting down: an n log n guaranteed sort, in place, unstable, compared with merge sort and quicksort.
- Hierarchical and density-based clusteringTwo more families of clustering: agglomerative hierarchical clustering (distance matrix, linkage criteria, dendrogram) and DBSCAN (radius, core, border and noise points); choosing between them and k-means.
- History of computingMilestones from the Pascaline to the microcomputer and the Web: inventors and contributions, technology generations (tubes, transistors, integrated circuits, microprocessors) and Moore's law.
- How a file system is organisedBlocks, superblock, inode table and data blocks, the three allocation schemes (contiguous, chained through a FAT, indexed), the directory as a file, fragmentation and journaling.
- How a system bootsThe sequence from power-on to the login screen: firmware, bootloader, kernel and initramfs, first process, services, and the messages that tell where it breaks.
- How an attack unfoldsThe seven phases of the attack chain, the defence that breaks each phase, ATT&CK, and the penetration test: black, grey or white box, its steps and the written authorisation required by the French Penal Code.
- HTML formsform, label, input and its types, validation attributes, and what the browser sends with GET or POST: knowing which fields are sent and how the request is written.
- HTTPThe language of the web: methods, status codes, headers and HTTP caching. What each part means, how to use it in real situations, and the classic traps (double submits, overly long caching, redirects).
- HTTP status codesThe 31 HTTP status codes worth knowing, from 100 Continue to 504 Gateway Timeout, both ways: each code's name, then each name's code. On the back, its family and when a server sends it. Names per RFC 9110.
- HTTP/2, HTTP/3 and QUICWhat the modern versions of HTTP change: HTTP/2 multiplexing, QUIC over UDP, connection migration and 0-RTT in HTTP/3, and when each one helps.
- HTTPS and TLSHow the web protects itself: what TLS guarantees, certificates and the chain of trust, the handshake, and the common problems (expired certificate, wrong name, mixed content, HSTS).
- HypervisorsType 1 and type 2 hypervisors, their role in sharing processor, memory and input-output, the virtual CPU, overcommitment, memory ballooning and live migration.
- IaaS, PaaS, SaaSThe five cloud characteristics according to NIST, the three service models, how responsibilities are split layer by layer between customer and provider, and pay-as-you-go billing.
- ICMPEcho messages (8 and 0), destination unreachable (3 and its codes), time exceeded (11) and redirect (5), how ping and traceroute use them, and path MTU discovery.
- Idempotency and retriesRetrying a request without paying twice: idempotency, idempotency keys, exponential backoff with jitter, and what “at least once” delivery implies. Scenarios and failures, every answer explained.
- IEEE 754 floating pointFractional binary and fixed point, the single-precision format (sign, exponent biased by 127, mantissa), double precision for comparison, special values, rounding errors and comparing floats.
- IndexesThe role of an index, the B-tree behind it, unique, composite and covering indexes, the leftmost-prefix rule, selectivity, write cost and the cases where the database cannot use one.
- InheritanceSingle inheritance in Java: superclass and subclass, the is-a relationship, inherited members and protected, the super(…) call and constructor order, the root class Object.
- Inner joinsCombining rows from two or three tables with INNER JOIN … ON, naming tables with aliases, joining a table with itself and spotting the Cartesian product left by a forgotten condition.
- INSERT, UPDATE, DELETEChanging the data in a database: adding rows with INSERT, changing them with UPDATE, removing them with DELETE, the trap of the forgotten WHERE and respect for foreign keys.
- Insertion sortSorting an array by taking the items one by one and inserting each in its place in the already sorted part: shifts, the inner loop, the best case on a sorted array and stability.
- Installing a network serviceThe fixed procedure, from package to test from a client: configure, start and enable, check that it listens, open the firewall, read the logs, using a web server and an SSH server as examples.
- Integers and two's complementUnsigned and signed integers on 8, 16 and 32 bits: representable range, sign and magnitude, one's complement, two's complement and sign extension.
- Integration testsChecking that modules that are correct on their own work together: interface faults, the big-bang, top-down and bottom-up integration strategies, stubs and drivers, and integration with a real database.
- Integrity constraintsThe families of rules that keep data correct, seen from the design side: domain, entity, referential, uniqueness, mandatory value and business rules, and what each guarantees. SQL syntax comes later.
- InterfacesThe interface as a method contract in Java: implements, several interfaces for one class, interface-typed variable, choosing between an interface and an abstract class, default method.
- Interfaces and peripheralsInput, output and storage peripherals, common connectors and interfaces (USB, HDMI, SATA, NVMe, PCIe, RJ45), serial versus parallel links, speeds, drivers and hot plugging.
- Internationalising a databaseMaking several languages and countries live in one database: server and client encoding, collation and sort order, case sensitivity, regional formats and time zones.
- InterruptsHardware interrupts, software interrupts and exceptions, how an interrupt is handled, the vector, the context, masking, and the choice between polling and interrupts.
- Inversion of controlWho calls whom: the Hollywood principle and its forms (callback, template method, event listener, dependency injection) and what sets a framework apart from a library.
- IP addresses, ports and NATHow machines find each other: IPv4 and IPv6 addresses, private networks and masks, ports and services, NAT and port forwarding, and the situations where a service stays unreachable.
- IP and routingHow a packet finds its way: IPv4 and IPv6 addresses, ARP on the local network, ICMP with ping and traceroute, and BGP between the Internet's operators.
- IPv4, masks and CIDRThe 32-bit address, the mask and the /n notation, network part and host part, network address, broadcast address, range and number of hosts, and classes A, B, C as a historical landmark.
- IPv6 on the networkNeighbour discovery replacing ARP, stateless autoconfiguration and the EUI-64 identifier, DHCPv6, the IPv6 header, splitting a /48 and living alongside IPv4.
- IPv6: addressesThe 128-bit address, hexadecimal notation and its two shortening rules, the /64 prefix and the interface identifier, the address types and the absence of broadcast.
- Isolation levels and anomaliesThe anomalies between concurrent transactions (dirty, non-repeatable and phantom reads, lost update) and the four levels of the SQL standard: what each one prevents and what it costs.
- Iterative versus recursiveThe same calculation written with a loop or with recursive calls: equivalence, stack memory, repeated work, moving from one form to the other and how to choose.
- IteratorsGoing through a collection without knowing how it is stored: the iterator and its three methods, the for-each loop, traversing a dictionary, and what happens when the collection is modified during the traversal.
- JavaScript: functions, arrays and objectsThe three ways of writing a function, default parameters, array methods (map, filter, reduce, slice, splice…) and objects, copied by reference.
- JavaScript: variables, types and equalitylet, const and var with their scope, primitive types and typeof, implicit conversions, == versus === and the falsy values.
- JSONThe syntax of JSON, JSON.parse and JSON.stringify, the difference from a JavaScript object and the access path to a nested value.
- K-means clusteringThe k-means algorithm from start to finish: choosing k, initialising, assigning, recomputing, stopping; inertia, the elbow, and sensitivity to initialisation, scales and cluster shape.
- K-nearest neighboursOne whole algorithm: measure the distances to the point to classify, keep the k nearest, vote or average; the choice of k, the effect of scales and the cost of a prediction.
- Kernel, drivers and user spaceThe layers of a system from hardware to application: kernel, drivers and modules, system calls, libraries, shell, and the border between kernel mode and user mode.
- Key-value storesThe key-value model on Redis: basic commands, five value types, key naming, expiry and eviction, and what the model forbids: finding data by its content.
- Kubernetes: configuration and storageNamespaces, ConfigMap and Secret as variables or mounted files, a pod's volumes, PersistentVolume, PersistentVolumeClaim and StorageClass, access modes, and what a StatefulSet adds.
- Kubernetes: pods and DeploymentsThe pod, the ReplicaSet and the Deployment, labels and selectors, the anatomy of a manifest, requests and limits, liveness and readiness probes, rolling updates and rollback.
- Kubernetes: Services and IngressWhy a pod has no stable address, the Service and its three types, selector and endpoints, port and targetPort, a Service's DNS name and the Ingress that routes HTTP traffic by host and path.
- Kubernetes: the architecture of a clusterThe control plane and the nodes, desired state and the reconciliation loop, how a pod is placed on a node (requested resources, taints, tolerations) and the path from a kubectl apply to the running container.
- Lambdas and closuresThe function as a value: anonymous function, function passed as an argument, function returning a function, closure, captured variables and the late-binding trap in a loop.
- Language modelsWhat a large language model does: split the text into tokens, predict the next token, append it and start again; context window, temperature, embeddings, the role of attention, pre-training then fine-tuning, and why it can state something false.
- Latency orders of magnitudeHow long does a read take from memory, a disk, across a data centre or an ocean? Rounded orders of magnitude to estimate without measuring, and what they mean for design. Every answer explained.
- Layered and hexagonal architectureLayered architecture and its dependency rule, then hexagonal architecture: domain at the centre, ports, primary and secondary adapters, and dependency inversion.
- Layout managersHow a window places its components without fixed coordinates: flow, row and column, border, grid, stack and anchored layouts, nesting of containers and behavior when resized.
- Levels A, AA and AAAThe three WCAG conformance levels, landmark criteria (alternatives, contrast, captions, keyboard) and the AA level targeted by the legal obligation, taken up by the RGAA.
- Library or frameworkWhat sets a library, which your code calls, apart from a framework, which calls your code: inversion of control, extension points, imposed life cycle and cost of leaving.
- Linear searchLooking for a value by checking the cells one by one: stopping as soon as it is found, the index returned or the not-found value, the first occurrence and the number of comparisons.
- Links and images in HTMLThe a element and its addresses (absolute, relative, anchor, mailto, tel), the img element and its alternative text, the figure/figcaption caption and the choice of image format.
- Lists and tables in HTMLBulleted, numbered and description lists, how to nest them, then tables: rows, cells, headers, merged cells and the role of each tag.
- Lists, sets, dictionariesThe three families of collections: the list (order, duplicates, index), the set (uniqueness) and the dictionary (key to value). Adding, accessing, removing, testing, and choosing the right collection for a need.
- Local storage on mobileFour storage options (preferences, private files and cache, SQLite database, key vault): picking the right one for each piece of data, knowing what survives closing, clearing the cache and uninstalling, and never writing a secret in plain text.
- LocksShared and exclusive locks, row or table level, their compatibility, SELECT … FOR UPDATE, pessimistic or optimistic locking, waiting and the deadlock the database detects and resolves.
- Locks and concurrent file accessStopping two instances of a script from stepping on each other: the race, the test-then-act flaw, atomic operations, mkdir, set -C, flock, the lock left after a crash and writing through a temporary file then renaming.
- Logging levelsThe levels of an application log from TRACE to FATAL, the threshold that filters, what to write at each level, the anatomy of a line and the difference from a plain print to the screen.
- Logic gatesThe seven gates NOT, AND, OR, NAND, NOR, XOR and XNOR: truth tables, equations, reading a small circuit, NAND universality and bitwise operators with their masks.
- Loops: for and whileRepeating a block a known number of times or while a condition holds: the range covered, early exit, nested loops, the infinite loop and the off-by-one error.
- Making a container's data persistThe ephemeral writable layer and the three mounts (named volume, bind mount, tmpfs); the -v and --mount options; the docker volume commands; what survives stop, rm and a new image.
- Making a script robustBash's strict mode, trap for cleaning up, mktemp, errors on the error output with an exit status, idempotence and shellcheck: knowing where a script stops and what it leaves behind.
- MalwareThe main malware families classified by propagation and payload, the five stages of an infection and how to recognise a family from its symptoms.
- Managing logsA log's chain from emission to search, syslog and its eight levels, structured logs, UTC time, the correlation id, rotation, retention and the personal data not to write.
- Measuring execution timeTiming a piece of code: timestamps before and after, repetition, measurement noise, measurements for several sizes, reading the order of growth and the traps that spoil a measurement.
- Media queriesThe meta viewport tag, @media with min-width and max-width, breakpoints, the mobile-first approach, orientation queries and preference queries (dark theme, reduced motion).
- Memory allocationA process's memory regions, static, automatic and dynamic allocation, malloc, calloc, realloc, free and sizeof in C, and the four classic faults: leak, double free, use after free and buffer overflow.
- Merge request and reviewThe pull request (merge request): its life cycle, a good description, automated checks, reading the diff, approval and plain or squashed merging; what to look for when reviewing.
- Merge sortDivide, sort each half, merge: merging two sorted sequences, the order of the recursive calls, the n log n cost, the auxiliary memory and stability.
- Message queues and workersDoing work later, without making the user wait: producers, consumers, acknowledgements, dead letters, at-least-once delivery and idempotency.
- Microprocessor and microcontrollerWhat separates a bare processor from a chip that carries its own memory and inputs and outputs, the system on a chip, embedded systems, real time and the main families x86, ARM, AVR and RISC-V.
- Migrating data and verifying the migrationMoving data from one database to another: inventory, column and type mapping, dry run, cutover and rollback; then the checks that prove nothing has changed.
- Mirroring and RAID levelsDisk mirroring and RAID levels 0, 1, 5, 6 and 10: usable capacity, failures tolerated, parity, rebuild and hot spare, synchronous or asynchronous remote mirroring, and why a mirror does not replace a backup.
- Mobile and embedded databasesThe database that lives inside the app: SQLite and its quirks, the WAL journal, schema migrations and offline synchronisation.
- Mobile interfaces and navigationThe mobile screen: densities and units (dp, sp), 48 dp touch targets, adaptive layouts; the four navigation patterns (stack, bottom tabs, drawer, modal window) and the back stack.
- Modelling a system with an automatonChoosing the states, events and transitions of a system described in plain language, adding outputs with a Mealy machine, then checking the model: unreachable state, deadlock, forbidden scenario.
- Modes of operationECB, CBC, CTR and GCM: how to encrypt a message longer than one block, the role of the initialisation vector, nonce and padding, error propagation and authenticated encryption.
- ModularitySplitting a program: one function per task, factoring out repeated code, grouping functions into modules, importing, and separating the main program from what can be reused.
- Modularity and packagesSplitting software into modules: packages, public interface and hidden details, visibility between packages in Java, packaging by layer or by feature, dependencies without cycles.
- Monitoring cloud resourcesThe metrics the platform provides, the period and the statistic, the alarm and its three states, health checks, saturation forecasting and cost budgets.
- MQTT and connected devicesThe protocol of sensors and connected devices: publish and subscribe through a broker, topics, delivery guarantees, retained messages and the last will.
- MVC, MVP, MVVMThree patterns that separate the interface from the business logic: the role of the model, the view, the controller, the presenter and the view-model, the direction of dependencies and what sets the three apart.
- N-tier architectureSpreading an application across several machines: one, two, three tiers and more, thin or thick client, and the difference between a tier (physical) and a layer (logical).
- NamingChoosing the names of variables, functions and constants: a name that states the intent, the writing conventions of Python and Java, a function's verb, a boolean's prefix and hunting down magic numbers.
- Native, hybrid or cross-platformThe four families of mobile apps (native, WebView hybrid, cross-platform, progressive web), what draws the screen in each, and the criteria that decide the choice: performance, hardware access, shared code, team and cost.
- Network and offlineNetwork calls off the main thread, timeouts and retries, then offline-first: the local database as source of truth, the queue of pending writes, synchronisation and conflicts.
- Network devicesRepeater, hub, bridge, switch, access point, router, modem and firewall: the layer where each one decides, what it reads and the domain it separates.
- Network diagnostic commandsping, traceroute, ip addr, ip route, ip neigh, ss, dig and nc, with their Windows equivalents: what each command tests, how to read its output and in which order to run them, from the bottom up.
- Network ports to knowThe 26 well-known ports asked about in networking and security (CCNA, Security+, system administration): SSH 22, DNS 53, HTTPS 443, RDP 3389… both ways. On the back, the transport (TCP or UDP) and what the service does.
- Network weaknessesEach classic attack on a local network and on the Internet with its remedy: sniffing, MAC table flooding, ARP spoofing, rogue DHCP server, VLAN hopping, IP spoofing, SYN flood, DNS poisoning, cleartext protocols.
- Networking a virtual machineThe virtual network card modes (NAT, NAT network, bridged, host-only, internal, not attached), the virtual switch, the address received, port forwarding and a clone's MAC addresses.
- Neural networksFrom neuron to network: weighted sum, bias, activation function, layers, forward propagation, parameter count, and what a single neuron cannot separate.
- Nielsen's 10 heuristicsNielsen's ten usability heuristics and the heuristic evaluation that uses them: linking a flaw to the heuristic it breaks, proposing the fix and judging severity.
- NomadThe Nomad orchestrator: servers and clients, the job, group, task hierarchy, drivers, the three job types, the HCL file, nomad job plan and run, evaluation and allocation, and the match with Kubernetes.
- Nondeterministic automata and determinizationThe nondeterministic automaton: several possible transitions, ε-transitions and ε-closure, acceptance by path, set of active states and the subset construction that makes it deterministic.
- NoSQL databasesKey-value, document, wide-column, graph: what each family does, when to choose it over a relational database, and what denormalisation and a free schema cost.
- NULL in SQLWhat NULL means, three-valued logic, IS NULL versus = NULL, NULL in calculations, aggregates, NOT IN and ORDER BY, and the COALESCE and NULLIF functions.
- Object storageStoring files and media outside the database: buckets, objects, pre-signed links, storage classes, lifecycle, versioning, and the mistakes that expose data or cost a lot.
- Object-relational mapping (ORM)What an ORM maps: class and table, attribute and column, association and foreign key, inheritance strategies; lazy or eager loading and the N+1 query problem.
- ObservabilityKnowing what happens in a system in production: logs, metrics, traces, the key signals to watch, percentiles rather than averages, and alerts that wake people for good reasons. Every answer explained.
- One-dimensional arraysThe 1D array: size, indices from 0 to n − 1, access and modification, traversal by index or by element, out-of-bounds access, shifting to insert or delete, and copying.
- Operators and precedenceArithmetic operators (floor division, modulo, power), comparison and logical operators, the order in which an expression is evaluated (precedence, associativity) and the short-circuit evaluation of logical operators.
- Optimising a programThe optimisation method (measure, target, change one thing, measure again), the five levers, memoization, Amdahl's law and the trade-off between time and memory.
- Optimising a queryThe method for a slow query: measure, read the plan, find the guilty operation, apply a remedy (index, usable predicate, useful columns, join, keyset pagination, statistics) and measure again.
- Orchestration: autoscalingThe instance group and its bounds, threshold and target-tracking policies, the observation window and the cooldown, replacing an unhealthy instance, and the conditions for it to work: a stateless service and a load balancer in front.
- Orchestration: infrastructure described as codeDescribe rather than click: the declarative approach, Terraform blocks, the init, plan, apply, destroy cycle, the state file, the dependency graph, idempotence, drift and cloud-init at first boot.
- Orders of growth of algorithmsConstant, logarithmic, linear, linearithmic, quadratic and exponential growth: ranking them, predicting the effect of doubling n and estimating an execution time.
- OSPFLink-state routing: neighbours through Hello messages, flooding of announcements and a shared database, shortest-path computation, cost derived from bandwidth, areas and area 0, the designated router and its election.
- Outer joinsLEFT, RIGHT and FULL OUTER JOIN: keeping rows without a partner by padding them with NULL, finding “those who have none” with IS NULL, and avoiding the trap of a condition put in WHERE.
- Owner, group and umaskA file's owner and group, chown and chgrp, who may change them, and the umask, which removes permissions from 666 and 777 at creation.
- Package managersPackages, repositories, dependencies and signatures; apt's subcommands, how it differs from dpkg, their dnf and rpm equivalents, and diagnosing the common errors.
- Packet filteringThe filtering rule, the first matching rule, the default policy, stateless and stateful filtering, and the input, output and forward chains.
- Page replacementWhat to do when memory is full: FIFO, LRU, clock and optimal, Belady's anomaly, swap space and thrashing.
- Particle systemsAn emitter, particles with a lifetime, forces, Euler integration step by step, recycling in an object pool and the loop that emits, updates, removes and draws.
- Partitioning (sharding)Spreading a database too large for one server: choosing the partition key, by range or by hash, avoiding hot partitions, rebalancing, and knowing when not to do it.
- Partitioning and isolating: namespaces and cgroupsWhat Linux namespaces hide, what control groups limit, the role of chroot and capabilities, and the out-of-memory killer: understanding what a container really is and reading an exit at 137.
- Partitions and mountingDisk, MBR or GPT partition table, partition, file system, formatting, mount point, mount, umount, fstab, lsblk, df, and names like /dev/sda1 or /dev/nvme0n1p2.
- Parts of a PCMotherboard, processor, memory, storage, graphics card, power supply, cooling and firmware: what each part does, the units on a spec sheet and diagnosing common faults.
- Pass by value or by referenceWhat a function really receives: a copy or access to the caller's data. Aliases, side effects on a list passed as a parameter, mutable and immutable types, input and output parameters.
- Password hashingWhy we hash instead of encrypting; salt, rainbow table, slow functions (bcrypt, scrypt, Argon2) and cost factor; verifying a password; what must never be done.
- Performance of a web applicationThe three Core Web Vitals signals (LCP, INP, CLS) and their thresholds, the rendering path and blocking resources, image and script weight, caching, compression and lazy loading.
- PermissionsNormal and dangerous permissions, declaring them in the manifest, asking at runtime, the rationale, repeated refusals, least privilege, and the iOS equivalent: knowing what to declare, when to ask and what to do with a refusal.
- Persisting an application's dataKeeping state between two launches: text file, CSV or JSON, object serialisation, preferences, embedded database; when to load and when to save; a model that ignores its storage.
- Persisting objectsMaking an object outlive the program: create, read, update, delete, an object's states (new, managed, detached, removed), DAO and repository, unit of work and when the SQL is really sent.
- PersonasA persona sheet (identity, context of use, goals, frustrations, digital comfort), primary and secondary personas, the anti-persona, and what grounds it: interviews and observations, not guesses.
- PipesThe pipe created by pipe and its two descriptors, how fork inherits it, end of file and SIGPIPE, capacity and blocking, dup2 to plug standard input or output, and the named pipe created by mkfifo.
- PointersPointers in C: the address and the & operator, declaration and dereferencing, the null pointer, arithmetic on arrays, passing by address and the dangling pointer.
- Polymorphism, overriding, overloadingDeclared type and actual type, dynamic dispatch, overriding an inherited method, overloading by signature, calling super.method(), casting and type testing in Java.
- Precomputing aggregatesComputing ahead what queries keep asking: aggregate tables and materialised views, the lattice of groupings, ROLLUP, CUBE and GROUPING SETS, measures that recombine or not, refreshing.
- Primary and foreign keysCandidate key, primary key, composite key, natural or artificial key; foreign key and referential integrity: what the database accepts and refuses on insertion, update and deletion.
- Procedural blocksThe block of a database procedural language (PL/pgSQL): DECLARE, BEGIN and END sections, variables and types taken from a column, SELECT INTO, IF, loops and output.
- Processes: states and PIDsWhat a process is as opposed to a program, the PID and PPID, the process tree, the ready, running, blocked and terminated states, the zombie, and reading ps output.
- Producer-consumer, readers-writers, dining philosophersThe three classic synchronisation problems, their risk and typical solution: the bounded buffer with two semaphores and a mutex, priority between readers and writers, the dining philosophers and their remedies.
- Producing imagesDraw a segment with Bresenham, filter by convolution (blur, sharpen, edges), threshold with the histogram, composite two layers with the alpha channel, generate a texture from noise.
- Profiling a programMeasuring before changing anything: timing a snippet, choosing between an instrumenting and a sampling profiler, reading own time and cumulative time, a flame graph, and avoiding misleading measurements.
- Programming with signalsSending a signal with kill or alarm, receiving it with sigaction and a handler, the mask and pending signals, pause, SIGCHLD to reap children and the functions allowed in a handler.
- Proxy and reverse proxyThe proxy that goes out on behalf of clients and the reverse proxy that stands in front of servers: what they are for, when to use them, what they cost and what breaks when they fail.
- PublicationFrom finished app to store: signing, version code and name, delivery format, listing, data declaration, test tracks, review, staged rollout and updates.
- Quality of serviceThe four measures of a link (throughput, latency, jitter, loss), what each use tolerates, best effort versus integrated and differentiated services, classifying and marking, queues, policing versus shaping and the token bucket.
- Querying a graph with CypherCypher, Neo4j's language: patterns, relationship direction, variable-length paths, aggregates, CREATE and MERGE.
- Querying a service from the client sidecurl, dig, nc, openssl s_client, ssh and sftp: composing the request, reading the answer, speaking a text protocol by hand and interpreting error messages.
- Querying Cassandra with CQLCQL, Cassandra's language: what the primary key allows, row order, ALLOW FILTERING, writes that overwrite and time to live.
- Querying MongoDB: find and aggregationMongoDB's query language: filters and operators, arrays, projection, sorting, then the aggregation pipeline stage by stage.
- Querying objects: OQL and object-relational SQLOQL queries from the ODMG standard, persistence by reachability and SQL's object extensions in PostgreSQL: composite types, arrays, table inheritance.
- QueuesThe queue and its first in, first out discipline: enqueue, dequeue, head, the circular array implementation, the double-ended queue, and telling when a situation calls for a queue rather than a stack.
- QuicksortThe pivot, Lomuto partitioning, recursion on both sides, the n log n average case, the quadratic worst case and the pivot choices that avoid it, an in-place and unstable sort.
- Rate limiting and backpressureProtecting a service that receives more than it can handle: limiting the rate, choosing the algorithm, telling clients to slow down, pushing back and shedding load before collapsing. Every answer explained.
- Reading a stack traceReading a Java stack trace: exception type and message, frames from newest to oldest, file and line number, library frames to skip and the Caused by chain.
- Reading and filtering textcat, less, head, tail, wc, grep, cut, sort, uniq and tr applied to a file: picking the right filter, the option that changes everything, and predicting the output on real data.
- Reading and writing filesReading and writing text files in Python: opening for reading, writing or appending, reading whole or line by line, writing, closing, relative or absolute path, line endings and opening errors.
- Real time: WebSocket, SSE and pollingPushing information to the browser: polling, long polling, Server-Sent Events and WebSocket, what they cost and how to keep them up at scale.
- RecordsThe structured type with named and typed fields: definition, dot notation access, array of records, nested records.
- RecursionA function that calls itself: base case, call on a smaller problem, call stack, going down and coming back up, and the runaway recursion that ends in an error.
- Redirections and pipesThe three standard streams, the redirections >, >>, <, 2> and 2>&1, /dev/null, the pipe and tee, and the order in which the shell applies them.
- References, equality, identityAn object variable is a reference: null, aliases, identity (==) versus equality (equals), a redefined equals, shallow or deep copy, in Java.
- Registers and instruction setA processor's registers, its flags Z, N, C and V, the families of instructions, how an instruction splits into an opcode and operands, and the difference between RISC and CISC.
- Regression testsChecking that a change has broken nothing: replaying the suite after every change, writing one test per fixed bug, comparing two reports, choosing the tests to replay and distrusting flaky tests.
- Regular expressionsRegular expressions as a notation for languages: letters, ε, ∅, union, concatenation, star, precedence, denoted language, equivalence of two expressions and Kleene's theorem.
- Regular expressions in practiceThe extended syntax of tools such as grep -E: dot, character classes, anchors, quantifiers, groups, alternation, escaping and greediness, with patterns tried on real lines.
- Relational databasesTables, indexes, transactions and ACID guarantees: how a relational database stays correct and fast, and what to know so as not to slow it down or corrupt it.
- Relationships and cardinalitiesLinking entities: binary, reflexive, ternary and attribute-carrying relationships, minimum and maximum cardinalities in Merise notation, reading both ways and the match with UML multiplicities.
- ReplicationKeeping several copies of data: the primary and its replicas, synchronous or asynchronous, replication lag, failover, and why a replica is not a backup.
- ReportingThe periodic report: what sets it apart from the dashboard and from on-demand analysis, its anatomy (parameters, breaks, detail, subtotals, grand total), its scheduled distribution, ROLLUP subtotals and reconciling two figures that contradict each other.
- Requirements elicitationElicitation techniques (interview, questionnaire, observation, workshop, analysis of existing material, mock-up), choosing the right one for a situation, types of questions and the stakeholders to ask.
- Reverse engineeringRecovering a software's design from its code: reverse engineering, redocumentation, restructuring, reengineering, call graph and class diagram.
- Review and walkthroughSoftware reviews in order of formality: informal review, walkthrough, technical review and Fagan inspection with its roles and six phases, and the checklist.
- RIPDistance-vector routing: hop-count metric (16 means infinity), updates every 30 seconds, the update rule, count to infinity and its remedies (split horizon, poisoning, triggered updates), RIPv1 against RIPv2.
- Risk analysis: the conceptsAsset, threat, vulnerability, feared event, likelihood and severity, the risk matrix, the four treatments, residual risk and the ISO 27005 cycle: putting the right words on a risk and deciding what to do with it.
- RobustnessWhat brings a mobile app down (exception, blocked main thread, process death, rotation, memory, unexpected response), reading a crash trace, testing and tracking crashes.
- Routes and controllersThe route table, path and query parameters, the order of routes, 404 and 405 responses, and the job of a controller: read the request, call the model, choose the response.
- RSAGenerating an RSA key pair on small numbers (n, totient, e, d), encrypting and decrypting by modular exponentiation, telling what is public from what stays secret, and understanding why factoring protects the encryption.
- Running mail: SMTP and IMAPThe chain from the client to the submission server, the transfer server, the mailbox and then IMAP or POP3; the SMTP dialogue and its codes, envelope and headers, MX, open relay and the queue.
- Running tasks in parallelLaunching background jobs with &, waiting for them with wait while keeping their exit codes, understanding the subshell and its lost variables, bounding parallelism with xargs -P and predicting the gain with Amdahl's law.
- rwx permissions and chmodThe nine rwx bits of the owner, the group and others, what they mean on a file and on a directory, symbolic and octal notation, chmod, and the setuid, setgid and sticky bits.
- SAA-C03AWS Solutions Architect – Associate Review (SAA-C03)The logical next step after the Cloud Practitioner: learn to design secure, resilient, high-performing and cost-optimized architectures on AWS. Original cards written from the official exam guide and the AWS documentation. Voyelle is not affiliated with Amazon Web Services. AWS and SAA-C03 are trademarks of their respective owners.
- SambaSamba's roles, its services, the structure of smb.conf and a share's settings, Samba accounts and Unix accounts, effective permissions, and the tools testparm, smbclient and smbstatus.
- Sample and test dataBuilding the data set that tests a schema and its queries: nominal case, edge cases, rows to reject, expected result written in advance, population script and anonymisation of real data.
- Scaling a systemKeeping a service up as traffic grows: scaling vertically or horizontally, why a stateless server is easy to duplicate, where the real bottleneck hides. Definitions, scenarios and trade-offs, every answer explained.
- Scaling machine learning upWhat changes when the dataset no longer fits in memory or training takes hours: algorithm costs, mini-batches, online learning, sparse matrices, spreading the computation and batch prediction.
- Scenario: a server, then a whole zone, goes down15 outages to analyse: single points of failure, health checks, database failover, zones, async replication, cascading failures, retry storms, deploys, certificates, DNS, stuck queues, backups, alerting. The cause, then the fix that makes the service resilient.
- Scenario: the database is overloaded15 investigations into a database at its limit: repeated reads, missing or excess indexes, replication lag, hot spots, locks, pagination, cache stampedes. For each, the cause then the typical solution, with the alternative and the pitfall.
- Scenario: the site crawls at peak hours15 investigations drawn from real incidents: measured symptoms (CPU, latency, bandwidth, errors), find the cause, then the typical solution. On the back: why, the alternative and the pitfall to avoid. Load balancers, sessions, CDNs, caching, message queues, rate limiting, connection pooling.
- Scheduled tasks: cron and timersReading and writing a crontab line, understanding cron's reduced environment, using at and scheduling with a systemd timer, including the missed task.
- Scheduling algorithmsHow the system picks the process that gets the processor: first come, shortest first, round robin, priorities; computing waiting and turnaround times, and recognising starvation and a badly chosen quantum.
- Scripts: exit codes$?, 0 for success, exit n, the conventional codes (1, 2, 126, 127, 128 plus the signal number), the &&, || and ; chains, and a pipeline's code: predicting what a line prints and no longer announcing a false success.
- Scripts: loopsfor over a list, wildcards or "$@", while and until, while read to read a file line by line, break and continue: tracing a loop and avoiding the trap of names containing spaces.
- Scripts: tests and conditionsif, elif, else and fi, the test command and its [ ] form, file, string and number tests, the &&, || and ! operators, and case: choosing the branch a script runs and spotting a badly written test.
- Scripts: variables and argumentsThe shebang line and the execute permission, assignment without spaces, single and double quotes, command substitution and integer arithmetic, read, and the parameters $0, $1, $#, $@: reading a Bash script and predicting what it prints.
- Secure architecturesDefence in depth, the dual-firewall DMZ, the bastion, sensors, the SIEM, the SOC that watches, the CERT that responds, and the six stages of incident response.
- sed and awkTransforming text on the command line: sed's substitution and addresses, awk's fields, patterns, BEGIN, END and totals.
- Segmentation and filteringTrust zones, least privilege applied to flows, the three ways to segment (subnets, VLANs, filtering between zones), the flow matrix and lateral movement.
- SELECT and WHEREQuerying a single table: choosing columns, expressions and aliases in SELECT, then filtering rows in WHERE with comparisons, AND, OR, NOT, BETWEEN, IN and LIKE.
- Selection and projectionThe vocabulary of relational algebra (relation, tuple, degree, cardinality) and the two operators that filter a relation: selection σ keeps rows, projection π keeps columns and removes duplicates.
- Selection sortSorting an array by finding, on each pass, the minimum of the unsorted part and swapping it into its first cell: trace, number of comparisons and swaps, stability.
- Semantic elementsheader, nav, main, section, article, aside, footer, figure, time and address versus div and span: choosing the element that says what each zone holds, and what that brings to screen readers and search engines.
- Semaphores and monitorsThe semaphore (counter and waiting queue), its P and V operations, its four uses, then the monitor: a lock and condition variables, wait, signal, broadcast and the loop around wait.
- Separating view and modelWhy the model knows nothing about the view, the model, view and controller roles in a graphical application, notification through an observer, and what it buys: tests without a window and several views of one model.
- Sequence diagramThe notation of the UML sequence diagram: lifelines, synchronous, asynchronous and return messages, activation bars, creation and destruction, alt, opt and loop fragments.
- Service interoperabilityInteroperability, compatibility and portability, the role of open standards, and the bridges between Linux and Windows: LDAP and Kerberos for identity, SMB for files, DNS, NTP and single sign-on.
- Sessions and cookiesThe cookie and its Set-Cookie and Cookie headers, its attributes (lifetime, scope, Secure, HttpOnly, SameSite), the server-side session and its identifier, and how to open, regenerate and destroy a session.
- Set operators in SQLUNION, UNION ALL, INTERSECT and EXCEPT: combining the results of two queries, column compatibility, duplicate removal and where ORDER BY goes.
- Sets as a data structureThe set as an abstract type (membership, add, remove, union, intersection, difference; no duplicates, no order) and its three implementations: hash table, sorted tree, bit vector, with the cost of each operation.
- Setting up a development machineThe plan of a development machine: editor, language and its version, Git and its identity, SSH key, per-project isolated environments, virtual machine, WSL and container.
- Setting up a host on the networkA host's four settings (address, mask, gateway, DNS server), static or supplied by DHCP, where they live on Linux and Windows, temporary or persistent settings, and how to check them.
- Shaping data for learningFrom the raw table to the matrix an algorithm accepts: individuals and variables, variable types, encoding, scaling and three distances (Euclidean, Manhattan, cosine).
- Shared memoryA segment common to several processes with shm_open, ftruncate, mmap with MAP_SHARED, munmap and shm_unlink, the lack of synchronisation and the semaphore, then choosing between pipe, signal and shared memory.
- Shell wildcardsThe patterns *, ?, [abc], [a-z], [!abc] and braces, the hidden files that * skips, the fact that the shell expands patterns before running the command, and the role of quotes.
- SocketsThe socket as a communication end, the TCP stream and UDP datagrams, the server calls (socket, bind, listen, accept) and the client calls (socket, connect), send and recv, sendto and recvfrom, and network byte order.
- Software quality characteristicsThe quality model of ISO/IEC 25010 (2011 version): its eight characteristics and their sub-characteristics, internal and external quality, one measure per characteristic, and the trade-offs between them.
- Sorting, DISTINCT, LIMITControlling the order and size of a result: ORDER BY on one or several keys, DISTINCT on the combination of displayed columns, LIMIT and OFFSET.
- Sound and videoSampling, quantisation, the Nyquist-Shannon theorem, aliasing and a sound's bitrate; compression; video as a sequence of images, key and predicted frames; codec and container.
- Specification by exampleSpecifying a business rule with concrete examples: key examples, example tables, boundary values, an example that reveals a missing rule and Gherkin scenarios the client can read.
- Specifying an interfaceThe specification file: screen inventory, zoning, navigation graph, component states (empty, loading, error, disabled), event-action-feedback table, style guide.
- SQL injectionHow an input pasted into a query changes that query: bypassed login, reading other tables with UNION, destruction; the prepared statement, least privilege for the SQL account and the false defences.
- SSH: keys and tunnelsConnecting to a server securely: the host key, key authentication, the agent, tunnels and the bastion, and the right reflexes when something looks wrong.
- Stack and heapThe two memory areas of an object program: the stack, with one frame per call, and the heap, where objects created by new live. References from one to the other, lifetime and overflow.
- StacksThe stack (last in, first out): push, pop, top, empty stack; array implementation; uses: bracket matching, undo, call stack, postfix expression.
- Star and snowflake schemasTwo shapes of one dimensional model: the star, the snowflake and the constellation, surrogate keys, denormalisation, and the star join that answers a question.
- Static or dynamic collectionsFixed-size array versus resizable list: capacity and size, appending, insertion, deletion, the cost of growing and choosing according to the need.
- Static routingThe routing table and its four columns, directly connected routes, the longest prefix, the default route, routes that must be written in both directions and the routing loop.
- Static versus instanceWhat belongs to the class and what belongs to each object: shared class attribute, static method without this, constant, calling through the class name and the static context error, in Java.
- Stored procedures and functionsCREATE PROCEDURE and CREATE FUNCTION, the IN, OUT and INOUT parameter modes, RETURN, calling with CALL or inside a SELECT, and what processing placed in the database gains and costs.
- Structural patternsThe seven structural patterns of the GoF catalogue: Adapter, Bridge, Composite, Decorator, Facade, Flyweight and Proxy. Intent, participants, a code example and patterns that look alike.
- SubnettingSplitting a block into equal subnets by borrowing bits, splitting into variable sizes from the largest need to the smallest, giving each subnet its network, range and broadcast, and aggregating neighbouring blocks.
- SubqueriesA query placed inside another: scalar subquery, list subquery with IN and ANY, EXISTS and NOT EXISTS, derived table in FROM, correlated or not, and the traps of NOT IN with NULLs.
- sudo and rootThe root account, su and sudo, the sudoers file edited with visudo, the sudo and wheel groups, the shape of a rule (who, where, as whom, what), least privilege and the trail sudo leaves.
- Supervised learning: classifying and predictingThe approach shared by every supervised model: features and target, classification or regression, training then predicting, decision boundary, data leakage and what each of the course's algorithms assumes.
- Supervised, unsupervised and reinforcement learningThe three learning modes and what separates them, labelled examples, unlabelled data or a reward, the agent-environment loop, self-supervision and badly specified rewards.
- SwitchingA switch's MAC address table: learning, forwarding, flooding, filtering, ageing; collision and broadcast domains; the loop and the spanning tree.
- System weaknessesThe six common weaknesses of a system and the fix for each: unpatched software, default passwords, needless services, excessive rights, default configuration, privilege escalation; reading a CVE entry and its CVSS score.
- systemd servicesWriting and driving a service unit: its three sections, ExecStart, Type, Restart, User, After, Requires, Wants, WantedBy, systemctl, unit states and journalctl -u.
- Tablespaces: where tables liveThe physical storage of a PostgreSQL database: tablespaces, files, 8 kB pages, dead rows, VACUUM, fill factor, measuring sizes and moving a table, with the Oracle vocabulary alongside.
- TCP in depth: connection and reliabilityThe TCP header field by field, the three-way handshake, byte and acknowledgement numbering, retransmission, closing with FIN or RST and the states of a connection.
- TCP in depth: windows and congestionThe receiver's window and the sliding window, the congestion window and its threshold, slow start, congestion avoidance and the reaction to the two kinds of loss (Tahoe, Reno).
- TCP or UDPThe two main ways to carry data: TCP, reliable and ordered, and UDP, light and without guarantees. How they work, their trade-offs, and how to choose for video, games, DNS or the web, up to QUIC and HTTP/3.
- TemplatesA template: HTML and placeholders; displaying a variable, looping, testing, including a fragment, inheriting a layout, and the automatic escaping of values.
- Test data setsDesigning a program's test data set: a test is an input and an expected result, with nominal cases, boundary cases and error cases, values chosen to reveal defects and a table of tests.
- Test doublesReplacing a dependency during a test: the five test doubles (dummy, stub, spy, mock, fake), programming an answer, verifying an interaction, and deciding what to double or leave real, with Mockito.
- Test-driven developmentThe red, green, refactor cycle: write a failing test first, then the simplest code that passes it, then clean up; small steps, triangulation, what the method brings and what it does not guarantee.
- Testing conformance to W3C standardsThe W3C HTML and CSS validators and how to read their messages, automatic accessibility audit tools (axe, WAVE, Lighthouse) and what they cannot see.
- Testing legacy codePutting tests on code that has none before changing it: characterization test, seams, breaking dependencies, sprout method, after Feathers.
- Text in HTMLHeadings, paragraphs, emphasis (strong, em), quotations, code, abbreviations, superscripts and entities: choosing the tag by what the text means, not by how it looks.
- The .gitignore fileWhat you do not version (compiled output, dependencies, secrets, editor files) and the syntax of .gitignore patterns: star, slash, double star, exclamation mark, and the case of an already tracked file.
- The 4 WCAG principlesPerceivable, operable, understandable, robust: the four WCAG principles, the guidelines filed under each and the habit of tying a real defect to the principle it breaks.
- The accessibility auditThe method of an audit following the RGAA: page sample, 106 criteria in 13 themes, status of each criterion, conformance rate, keyboard and screen reader tests, accessibility statement.
- The activity diagramDescribing a flow with an activity diagram: actions, initial and final nodes, decision and merge with guards, fork and join, swimlanes per actor.
- The actors of a systemThe actor in the UML sense: a role outside the system that interacts with it, primary or secondary, human or external system, generalisation between actors and the system boundary.
- The anomalies of a redundant tableThe three anomalies of a redundant table (insertion, update, deletion), the redundancy that causes them and the decomposition that removes them, on a flat table of enrolments and orders.
- The binary search treeThe ordering property, search, insertion, deletion in its three cases (leaf, one child, two children), the in-order traversal that returns the keys sorted, the height and the degeneration into a list.
- The box modelThe four layers of a box (content, padding, border, margin), box-sizing, the difference between block, inline and inline-block, and the collapsing of vertical margins.
- The Caesar cipherShifting the alphabet modulo 26: encrypting, decrypting, finding the key from a plaintext and ciphertext pair, the key space and exhaustive search.
- The CASE toolWhat a data modelling tool does: enter the conceptual model, check it, derive the logical then physical model, generate the SQL script, reverse-engineer an existing database and maintain the dictionary.
- The catalogue of graphical componentsThe fifteen components of a graphical interface (button, label, text field and text area, checkbox, radio button, drop-down list, list, slider, spinner, progress bar, menu, tabs, dialog box, table, tree) and choosing the one that suits an input.
- The CDNServing content close to users: the origin and edge servers, cache lifetime, purging, versioned file names, and the pitfalls of a shared cache.
- The client-server modelWho listens and who takes the initiative, the socket, listening port and ephemeral port, the five values that identify a connection, one server for many clients, stateful or stateless, and peer-to-peer by contrast.
- The client-side framework: rendering and reactivityWhat the client-side framework does by itself, read on React: declarative rendering, state and re-rendering, virtual DOM and keys, effects and dependencies, lifecycle, one-way state store.
- The conceptual data modelThe full approach, from business rules to the entity-relationship diagram: the three levels (conceptual, logical, physical) and the five classic faults of a conceptual model.
- The concurrent paradigmThe concurrency models of languages and frameworks: threads and pools, promises, async/await and the event loop, actors; concurrency versus parallelism and the race condition.
- The concurrent serverThe four server models (iterative, one process per client, one thread per client or a thread pool, multiplexing with select), reaping children, closing descriptors and the limits of each model.
- The CSS cascade and inheritanceHow the browser chooses between declarations that contradict each other (origin, !important, specificity, order), which properties pass down to children, and the three ways to attach CSS to a page.
- The cube and OLAP operationsThe data cube (cell, dimension, level, member) and its operations: roll up, drill down, slice, dice, pivot; the three storages MOLAP, ROLAP and HOLAP.
- The decision dashboardA steering screen: the indicator (definition, target, threshold, period), the three levels of decision, the reading order of a screen, the context of every figure and the difference between an indicator that helps decide and a flattering figure.
- The deductive database: facts and rulesA database made of stored facts and rules that deduce others, in Datalog: reading a rule, asking a query, deducing by hand what a non-recursive rule produces, and relating it to relational algebra.
- The digital image and its formatsPixel, definition, resolution, colour depth and alpha channel; raster or vector images; lossless and lossy compression; BMP, PNG, GIF, JPEG and SVG, and what each is used for.
- The distributed paradigmA program spread over several machines: message passing, remote procedure calls, partial failure, timeouts and retries, no guaranteed arrival order and the fallacies of distributed computing.
- The DMZThe three zones (Internet, DMZ, internal network), which servers go in the DMZ, the flows allowed and forbidden between zones and the two possible setups: a three-legged firewall or two firewalls in series.
- The DOM and eventsThe document tree as seen from JavaScript: selecting, reading and modifying elements, listening to events, their propagation, preventDefault and delegation.
- The domain modelThe conceptual classes taken from the business vocabulary, their attributes, named associations and multiplicities: an analysis model, with no methods and no technical choices.
- The embedded paradigmProgramming a constrained machine: main loop with no operating system, interrupts and flags, real-time kernels and deadlines, registers and bit masks, energy budget and watchdog.
- The environmental and social impact of a projectAssessing from the specification what a piece of software costs the environment and society: life cycle, weight of devices, rebound effect, functional sobriety, accessibility, inclusion and privacy.
- The event loop and listenersHow a graphical interface reacts: events arrive in a queue, a loop hands them out one by one on the UI thread, the listeners registered on the source run, the event propagates, and a long task freezes everything.
- The execution planReading the output of EXPLAIN and EXPLAIN ANALYZE: the tree of operations, sequential or index scans, joins, sorting, cost, estimated versus actual rows and statistics.
- The families of AI: symbolic and learningTwo ways to build an AI, writing the rules or having them learned from examples: expert system, inference engine, what each family can explain and demands, and the key dates from 1950 to 2022.
- The fetch-decode-execute cycleThe three phases of the cycle on a small accumulator machine: the role of the program counter, the instruction register and the accumulator, stepping through short programs, clock and frequency.
- The firewallWhat a firewall is, its five families (stateless filter, stateful filter, proxy, web application firewall, host firewall), where to place it and what it does not stop.
- The functional paradigmPure functions and side effects, immutability, higher-order functions (map, filter, reduce), composition, recursion in place of loops and lazy evaluation: reading a program built from functions and predicting what it returns.
- The Hamming codeThe Hamming distance and what it lets a code detect and correct, the Hamming (7,4) code: check bits, encoding, syndrome, correcting one error, and the false correction when two bits have flipped.
- The hash tableHash function, buckets, collisions and their two resolutions (chaining, linear probing), load factor and resizing, average and worst-case cost, the contract between equality and hashing of a key.
- The heap and the priority queueThe priority queue as an abstract type and the binary heap that implements it: heap property, complete tree stored in an array (parent and child indices), insertion by sifting up, extraction by sifting down, costs.
- The Hill cipherEncryption by blocks of two letters with a 2 × 2 matrix modulo 26: encrypting, the condition for a matrix to be a key, the decryption matrix and the known-plaintext attack.
- The IP headerThe 20 bytes of the IPv4 header field by field, the decreasing TTL, the checksum, fragmentation and the MTU.
- The join in relational algebraNatural join, equijoin and theta join: which attributes are matched, which schema and how many tuples you get, and what happens to tuples that have no partner.
- The journey of a web requestWhat happens between typing an address and seeing the page: DNS, the TCP connection, TLS encryption, the HTTP request and response, rendering. Each step through its definition, real situations and what breaks when it fails.
- The LDAP directoryThe directory versus the database, the tree and its entries, distinguished and relative names, object classes and attributes, the LDIF format, operations, and search by base, scope and filter.
- The lifecycle of a screenThe seven lifecycle methods of an Android activity (onCreate, onStart, onResume, onPause, onStop, onDestroy, onRestart), the events that trigger them (opening, going home, rotation, incoming call, process death) and saving state.
- The limits and biases of AIWhere an AI goes wrong and why: invented statements, data biases (historical, representation, measurement, selection), drift over time, opacity, adversarial examples, energy cost; the safeguards (human review, per-group measurement, monitoring in service) and the four risk levels of the European AI regulation.
- The Linux directory treeThe root and the standard directories (/etc, /var, /home, /usr, /dev, /proc, /tmp…), the difference between absolute and relative paths, and the meaning of “.”, “..” and “~”.
- The load balancerSpreading traffic across several servers: the algorithms, layer 4 versus layer 7, health checks, sessions, and what happens when a server or the balancer itself fails.
- The master-detail interfaceA list and the detail of the chosen item: selection as the link, the no-selection state, editing with save and cancel, updating the list, and the two-screen version on a phone.
- The mathematics of learningThe tools that make a model learn: dot product, loss function, gradient, learning rate, gradient descent, chain rule, backpropagation and softmax.
- The memory hierarchyFrom registers to the hard disk: capacity, speed, cost and volatility of each level, the cache's role, temporal and spatial locality, hits and misses, average access time.
- The MVC pattern on the serverModel, view and controller in a web application: who does what, the path of a request from the router to the response, and the classic layering mistakes.
- The object database: identity and navigationWhy an object database exists: the mismatch between a graph of objects and tables, the object identifier, persistent objects, and navigating from reference to reference instead of joining.
- The operating system: role and familiesWhat an operating system does between programs and hardware, and the main families: Unix and BSD, Linux and its distributions, macOS, Windows, Android, iOS.
- The OSI and TCP/IP modelsThe layers of a network exchange on a real frame: an HTTP request decoded byte by byte, the four nested envelopes, what each device reads and rewrites along the way, and which layer a failure belongs to.
- The phone's sensorsSeven sensors (accelerometer, gyroscope, magnetometer, GPS, proximity, light, barometer): what each measures, in which unit and on which axes, how to subscribe to its readings and why to unsubscribe.
- The refactoring catalogueThe usual refactorings from Fowler's catalogue and the smell each one cures: extract, rename, move, introduce a parameter object, replace a conditional with polymorphism.
- The refactoring processRefactoring without changing behaviour: test safety net, small steps, one refactoring per commit; technical debt and its quadrants; refactor or rewrite, gradual replacement.
- The request-response cycleWhat happens between a click and the displayed page: the request, the processing on the server, the response, the page's secondary requests and the absence of state between two requests.
- The scenarios of a use caseThe written description of a use case: actor, preconditions, trigger, numbered main scenario, alternative and exception extensions attached to a step, postconditions.
- The server-side frameworkThe common blueprint of a server-side framework, read on Express and Spring Boot: routes, middleware or filters, controller, injection, data access, convention over configuration, and the path of a request.
- The single-page applicationThe single-page application versus the multi-page application; client-side rendering, server-side rendering, static generation and hydration, and what they change for first display, search ranking and the back button.
- The SOLID principlesThe five object-oriented design principles (single responsibility, open-closed, Liskov substitution, interface segregation, dependency inversion): stating them, recognising a violation and fixing it.
- The stack and function callsThe call stack and its pointer, pushing and popping, what a call and its return do, the stack frame, the calling convention and stack overflow.
- The stages of a pipelineStages and jobs, the canonical order, parallelism, dependencies as a graph, run conditions, blocking or tolerated failures, duration and critical path, on real .gitlab-ci.yml files.
- The state machine diagramAn object's behaviour over time: states, initial and final states, transitions triggered by an event, guards, effects, and entry and exit activities.
- The steps of installing a systemThe plan of a Linux installation, from the downloaded image to the first boot: checking the checksum, making the bootable drive, partitioning, installing the bootloader, living next to Windows.
- The structure of an HTML documentThe fixed skeleton of a web page: doctype, html, head and body, the vocabulary of markup (element, tag, attribute, empty element) and the tree the browser builds from it.
- The system sequence diagramFor one scenario of a use case, the events the actor sends to the system seen as a black box, its replies, and the alt, opt and loop fragments.
- The test pyramidThe three test levels, from the unit test to the end-to-end test, the pyramid shape that spreads their number, their duration and the precision of their diagnosis, and the ice cream cone to avoid.
- The use case diagramThe UML use case diagram: the use case (an actor's goal, named with a verb), the system boundary, the association between actor and use case, the include and extend relationships and generalisation.
- The Vigenère cipherEncryption with a repeated key, decryption, finding the key length with the Kasiski test and the index of coincidence, and the return to several Caesar ciphers.
- The virtual machine: disks, images and snapshotsWhat a virtual machine is made of (configuration, virtual disk, ISO image), fixed or dynamic allocation, copy-on-write snapshots, full or linked clones and templates.
- The WITH clauseCommon table expressions: naming a query, chaining several, what WITH brings compared with a nested subquery, and WITH RECURSIVE to walk through a hierarchy.
- ThreadsWhat a thread is and how it differs from a process, what threads share or do not, the pthread_create and pthread_join calls, and the race condition when two threads touch the same variable.
- Throwing, catching and propagating an exceptionJava's exception mechanism: throw, try, catch, finally, climbing the call stack to the first compatible catch, the order of catch blocks and try-with-resources.
- Training, evaluating, overfittingThe cycle of a training run: training, validation and test sets, epoch and batch, error curves, underfitting, overfitting and their remedies.
- Transforming data for analysisSix table transformations written in SQL: filtering, deriving a column, aggregating to a grain, joining, pivoting and binning; their order and the number of rows each one returns.
- Transmission mediaTwisted pair and its categories, RJ45 wiring, single-mode and multimode fibre, coaxial cable and radio: speed, reach and sensitivity to disturbance.
- Traversal and accumulationThe loop patterns over an array: sum, product, count, mean, minimum and maximum with their index, the “all” and “at least one” flag, and above all the right starting value of the accumulator.
- TriggersThe trigger: event (INSERT, UPDATE, DELETE), timing (BEFORE, AFTER, INSTEAD OF), row or statement level, OLD and NEW, its uses (log, computed value, rule) and its dangers (cascade, hidden logic).
- Two-dimensional arraysThe 2D array: rows and columns, m[i][j] access, nested loops, traversal by rows, by columns or along a diagonal, neighbours of a cell and array of arrays.
- Types of attackThe axes along which an attack is classified, the property it targets (confidentiality, integrity, availability) and ten families: eavesdropping, spoofing, man in the middle, denial of service, brute force and dictionary, social engineering, injection, privilege escalation, ransomware and supply chain.
- Types of maintenanceThe four types of maintenance in ISO/IEC 14764, their share of the effort, Lehman's laws and how a change request is handled.
- Types of virtualisationThe techniques for running one system inside another (emulation, full virtualisation, paravirtualisation, hardware assistance, OS level), what each one requires and what can be virtualised.
- Typing user inputEvery input arrives as a string: explicit conversion to the expected type, strict comparison, allowlist of values, rejection rather than repair, and the pitfalls of loose comparison.
- Typography in CSSfont-family and its fallback stack, generic families, @font-face, size, weight, style, line height, alignment, letter spacing and readable line length.
- UDPThe 8-byte header and its four fields, the lack of connection, acknowledgement and ordering, the checksum, what the application must do itself and the uses (DNS, DHCP, voice, QUIC).
- Union, intersection, differenceThe three set operators of relational algebra: the schema compatibility condition, what each returns, the difference that is not commutative, and its use to express “those who have not”.
- Unix signalsThe SIGHUP, SIGINT, SIGQUIT, SIGKILL, SIGSEGV, SIGTERM, SIGCHLD, SIGCONT, SIGSTOP and SIGTSTP signals: who sends them, what they do by default, which ones a program can catch, and the kill, killall and pkill commands.
- Usability of a web applicationMaking a web application easy to use: navigation, forms, screen states (loading, empty, error, success) and mobile-first design with 44 px touch targets.
- Usability testsMeasuring whether real people can use the application: the protocol of a user test, thinking aloud, the number of participants, measures of success, time and errors, and the SUS questionnaire.
- Usage scenariosThe story of a user reaching a goal: actor, context, trigger, steps, outcome; nominal scenario and variants; breaking a task down into subtasks.
- Use case diagramThe notation of the UML use case diagram: primary and secondary actors, use cases, the system boundary, include, extend and generalisation relationships.
- User interface testsAutomating a test that drives the interface like a user with Selenium or Playwright: locating an element, acting, waiting, checking, structuring with the Page Object pattern and hunting fragile tests.
- User stories and acceptance criteriaThe user story (as a, I want, so that), the six INVEST qualities, verifiable acceptance criteria (Given, When, Then) and splitting a story that is too big.
- Users and rolesCREATE ROLE and CREATE USER, login roles and group roles, the LOGIN, SUPERUSER and CREATEDB attributes, membership and inheritance, the owner of an object and the principle of least privilege.
- Variables, types and assignmentWhat a variable is, the basic types, assignment and its pitfalls, swapping two variables and type conversions: reading each line and predicting what it does.
- ViewsCREATE VIEW and DROP VIEW: a view as a stored query and not a copy, its uses (simplify, protect, isolate from the schema), updatable or not, WITH CHECK OPTION and the materialized view.
- Virtual memory and pagingVirtual and physical addresses, page and frame, page number and offset, page table, MMU and TLB, present bit, page fault and segmentation fault: translating an address and saying who does what.
- Virtual networksHow containers talk to each other: the virtual interface pair and the host bridge, Docker's network drivers, VXLAN encapsulation between hosts, Kubernetes' network model and the NetworkPolicy.
- Virtualised architecturesServer consolidation, the hypervisor cluster and its shared storage, live migration, high availability, N+1 sizing, the virtual desktop and hyperconvergence.
- Visualisation librariesThe three families of libraries (low-level, declarative, mapping) and the mechanisms they share: the scale, the axis and the binding of data to marks.
- Visualising big dataShowing more points than the screen has pixels: overplotting and its remedies (transparency, sampling, bins, small multiples, logarithmic scale), aggregating before display and the overview, zoom, details rule.
- VLANsWhy segment, access and trunk ports, the 802.1Q tag, the native VLAN and routing between VLANs with subinterfaces or a layer 3 switch.
- Von Neumann architectureThe stored-program computer model: control unit, arithmetic and logic unit, a single memory, input-output and three buses, compared with the Harvard architecture, with its bottleneck.
- VPNs: IPsec and WireGuardLinking networks and remote workers through an encrypted tunnel: site to site or remote access, IPsec or WireGuard, split tunnelling, and the classic failures (NAT, MTU, routes).
- Watching and controlling processesFinding, testing, bounding and stopping a process from a script: pgrep, pkill, kill -0, timeout, nice, ulimit, the /proc directory, the PID file, the daemon and the zombie.
- Web development toolsThe browser developer tools' panels and the symptom each one sheds light on, the package manager and its dependencies file, the development server, the bundler, the linter and the formatter.
- Web languages for dataDrawing data in a web page: SVG elements and their coordinate system, Canvas, choosing between the two, and loading CSV or JSON data.
- Web securityThe attacks every web service must fend off: SQL injection, XSS, CSRF, session theft, badly stored passwords, and the protections that really work. Mechanisms, scenarios and defences, every answer explained.
- Web service architectureThe chain that serves a site: web server, virtual hosts, reverse proxy, application server, database, TLS termination and logs, in two and three tiers.
- What a flaw costsFour programming flaws (buffer overflow, integer overflow, unchecked input, unreleased resource) and what they cause for confidentiality, integrity and availability, then for the organisation.
- Wi-FiThe 802.11 generations, bands and their channels, SSID and BSSID, a station joining an access point, CSMA/CA and the hidden node, and the WEP, WPA, WPA2 and WPA3 protections.
- Wide-column storesThe wide-column model on Cassandra: keyspace, table, partition key and clustering columns, one table per query, and how it differs from the column storage of data warehouses.
- Window functionsThe OVER clause with PARTITION BY and ORDER BY, ROW_NUMBER, RANK, DENSE_RANK, LAG, LEAD and running totals with SUM … OVER: computing beside each row without collapsing it, unlike GROUP BY.
- Working out a complexityCounting the operations of iterative code: statements in sequence, a single loop, nested loops, a halving loop, a hidden call inside a loop, best and worst case, memory used.
- Writing a DockerfileThe instructions FROM, WORKDIR, COPY, ADD, RUN, ENV, ARG, EXPOSE, USER, CMD and ENTRYPOINT; the build context and .dockerignore; one layer per instruction, the build cache and docker build -t.
- XSS vulnerabilitiesScript injection into a page: stored, reflected and DOM-based XSS; what the attacker gains; output escaping according to context, the CSP policy and the HttpOnly cookie.
- xUnit assertionsThe assertion family of xUnit frameworks: equality, truth, nullity, identity, arrays, floats with a tolerance, expected exception, failure message, and the difference between a failure and an error.
Earth and space sciences
Economics and management
- A project's budgetCosting a project: daily rate, budget lines, capital and running expenses, contingency, total cost of ownership, and tracking with budget, committed, actual and remaining spend.
- An enterprise package's language: models, fields and queriesWhat you write when you program inside an enterprise package, using Odoo in Python as the example: models and fields (relations included), the four operations on records, recordsets and the prefix-notation filter.
- An ERP implementation projectThe plan of an ERP project, from scoping to start-up support: choosing the vendor, fit-gap analysis, configuration, data migration, acceptance testing, training and cutover, with the people involved, the cost items and the known causes of failure.
- Auditing and reporting on the information systemAn information system audit assignment, from engagement letter to follow-up, evidence and the five-part finding, the COBIT, ITIL and ISO 27001 frameworks, and reporting to management: summary, priorities, action plan.
- Backlog and estimationThe product backlog (ordered, refined, detailed at the top), relative estimation in points, planning poker, velocity and delivery forecasting, ordering by value and effort.
- Breaking the work downThe work breakdown structure: splitting a project into packages then tasks, the 100% rule, a task with a deliverable, an owner and an estimable duration, and dependencies between tasks.
- Budget management of an IT departmentThe budget as a forecast you follow: the budget cycle, run and build, committed and actual, favourable and unfavourable variances, volume and price variances.
- Building a teamWhat sets a team apart from a group, the effect of size on communication and Brooks's law, Belbin's nine roles, the skills matrix and the stages of a team's life according to Tuckman.
- Building an argumentThesis, argument and example, the three means of persuasion, concession and rebuttal, logical connectors and the main fallacies: defending a choice in a structured way and spotting faulty reasoning.
- Business process managementWhat a process is, its elements, its three families, process maps, process-based organisation and the improvement cycle: describing, measuring and diagnosing a process.
- Business processes and BPMNThe business process (trigger, activities, actors, outcome) and the BPMN 2.0 notation: pools and lanes, events, tasks, exclusive, parallel and inclusive gateways, sequence flows and message flows.
- Change management methods and toolsLewin's three phases and force field, Kotter's eight steps, ADKAR, the change curve, the impact study and the stakeholder map: choosing the model or tool that fits the situation.
- Choosing an IT investmentDeciding on a project by its cash flows: schedule, discount rate, net present value, internal rate of return, payback period, return on investment and criteria that cannot be priced.
- Configuring an enterprise packageAdapting without programming: the ladder of answers to a need, the master data to set up first, configurable business rules and rights (groups, per-model rights, per-record rules).
- Corporate social responsibility (CSR)What CSR is and its three pillars, the ISO 26000 standard and its seven core subjects, the French and European framework, and how to tell a proven commitment from a greenwashing claim.
- Creating a new productFrom idea to market: the five stages of user-centred design, the value proposition canvas, the minimum viable product, the build-measure-learn loop and the product life cycle.
- Cryptocurrencies and uses of the blockchainWhat a shared ledger without a trusted third party allows: bitcoin and its capped supply, ether and smart contracts, stablecoins and non-fungible tokens, wallets and exchanges, risks, public and private chains, when a blockchain is justified, and the European MiCA regulation.
- Customer relationship managementThe funnel from lead to customer, the three sides of a CRM tool, recency-frequency-monetary segmentation, and five indicators.
- Data business modelsWhere a digital service's money comes from: targeted advertising, subscription, free with a paid option, commission, API. The mechanisms behind it: two-sided markets, network effects, marginal cost, lock-in.
- Depreciation of fixed assetsWhat is capitalised and what is expensed, the depreciable base, straight-line depreciation with pro rata, net book value and the depreciation entry.
- DerivativesA derivative and its underlying, four families (forwards, futures, options, swaps), three uses (hedging, speculation, arbitrage), premium, strike, payoff profile and leverage.
- Developing a module for an enterprise packageAdding to an enterprise package without touching its standard, using Odoo as the example: a module's anatomy, dependencies, extending a model and a screen, computed fields, access rights and surviving a version upgrade.
- Digital ethicsThe ethical questions raised by a digital product and the tools to answer them: reasoning frames (consequences, duties, virtues), deceptive interfaces, the attention economy, algorithmic bias, privacy by design, accessibility and responsibility.
- Digital identity and online reputationWhat the web says about you and how to control it: the three identities, traces, searching your own name, the remedies (deletion, erasure, delisting, the data protection authority, image rights) and the professional presence to show.
- Digital sobrietySobriety, efficiency and offsetting told apart; the levers of a person and of an organisation ranked by order of magnitude, and the actions whose gain is negligible.
- DiscountingThe time value of money: present value of a future sum, discount rate and factor, streams of cash flows and constant annuities, comparing sums at different dates.
- Double-entry bookkeeping and the chart of accountsThe principle of double entry, the direction of accounts, the classes of the French chart of accounts and the chain from journal to ledger to trial balance: recording an entry and knowing why it balances.
- Eco-designing a digital serviceThe eco-design approach, from need to end of life: functional unit, sorting features, compatibility with old devices, the themes of the general framework and measurement with EcoIndex.
- Economic agents and the circular flowThe six institutional sectors, what each one does, the real and monetary flows that link them, the three markets of the circular flow, disposable income and the savings rate.
- Economic policiesThe four goals of Kaldor's magic square, fiscal and monetary policy, deficit, debt and the multiplier, the trade-off between inflation and unemployment: choosing the right measure for a given economic situation.
- Employers: IT services firms, software vendors, IT departmentsThe main employers in tech, what each one sells, and the ways of working: time and materials, fixed price, application maintenance outsourcing. Who pays, who directs and who invoices when an IT services employee is on assignment.
- Enterprise architecture: urbanising the information systemOrganising an information system like a city: four views, zones, districts and blocks, application mapping, urbanisation rules and the path from the current state to the target.
- Estimating effortEffort, duration and deadline, the person-day, the estimation methods (analogy, experts, three points, parametric) and the traps that derail a schedule: Brooks's law, optimism bias.
- Explaining to non-specialistsExplaining a technical notion to someone who does not know it: sizing up the audience, starting from the familiar, choosing an analogy and stating its limits, giving the essentials first, and knowing where simplifying turns into saying something false.
- Expressing the needFunctional analysis of the need: need versus solution, the 5W1H questions, the horned-beast diagram, the octopus diagram, main and constraint functions, criterion, level and flexibility, scope.
- Financial modellingBuilding a model in a spreadsheet: assumptions, calculations and results kept apart, financial functions (PV, FV, PMT, NPV, IRR), cash flow forecast, scenarios, sensitivity analysis and simulation by random draws.
- Financial ratiosTwelve ratios in four families (profitability, structure, liquidity, turnover): their formula, their usual benchmark and the reader they speak to.
- Full costingThe cost-centre method: direct costs charged, indirect costs allocated in two stages, cost driver and its rate, then the cascade from purchase cost to production cost, cost price and product profit.
- Functional, divisional and matrix structuresReading an organisation chart, understanding unity of command, and telling functional, divisional and matrix structures apart: strengths, limits and how to choose.
- Generic strategiesCost leadership, differentiation and focus: their levers, their risks, working out an experience effect and the trap of being stuck in the middle.
- Globalisation and tradeComparative advantage, free trade and protectionism, the balance of payments, exchange rates, multinational firms, global value chains and the WTO: reading a country's trade and its effects.
- Growth and GDPValue added, the three approaches to GDP, GDP in value and volume, growth and its sources, and the limits of GDP as a measure of well-being.
- Handling a conflictThe sources and degrees of a conflict, the five Thomas-Kilmann styles, the I-message, the DESC method, assertiveness and calling on a third party.
- How an IT services firm and an IT department are organisedThe roles in an IT services firm and the four figures that steer it, the units of an IT department, projects versus keeping the lights on, outsourcing, and computing a consultant's margin.
- How employers recruitRecruitment channels and stages, possible tests, and the ways in seen by the candidate: internship, apprenticeship, contracts.
- How start-ups make their economics workWhat sets a start-up apart from a small business, the minimum product, measure and pivot approach, the J-shaped cash curve, funding rounds in order, dilution and the indicators that steer the money: cash, acquisition cost, customer value, churn.
- Ideation and product visionFrom idea to minimum product: the five steps of design thinking, divergence and convergence, brainstorming, the product vision statement, the minimum viable product, the build-measure-learn loop and the roadmap.
- Inflation and purchasing powerThe price index and the inflation rate, disinflation, deflation and stagflation, the causes of inflation, purchasing power, the real interest rate and who gains or loses when prices rise.
- Intermediate management balancesThe cascade that leads from sales to net income: trading margin, value added, gross operating surplus, operating income, ordinary income before tax, net income, and self-financing capacity.
- Internal control and the information systemThe arrangements that keep operations, accounts and compliance under control: the five COSO components, preventive, detective and corrective controls, segregation of duties, the audit trail, IT general controls and the three lines model.
- Interoperability between applicationsGetting an information system's applications to exchange: levels of interoperability, ways to integrate, pivot format, enterprise bus, electronic document interchange and field mapping.
- Job families in techThe seven job families in tech and, for each, the landmark jobs and their mission: development, operations, data, security, quality, design, management.
- Judging a sourceReliability criteria, primary, secondary and tertiary sources, fact and opinion, reading a web address and the standing of a developer's sources: deciding what to trust, and why.
- KanbanThe Kanban method applied to software: visualising the flow, limiting work in progress, pulling work, spotting the bottleneck, measuring lead time, cycle time and throughput, reading a cumulative flow diagram.
- Keeping watchThe five-step watch cycle, the four kinds of watch, pushed or pulled collection, the tools (feeds, alerts, newsletters, repository releases, security bulletins) and information overload.
- Leading the teamGetting a project team to work: RACI matrix, project meetings (kick-off, progress meeting, review), usable decision records, Tuckman's four stages.
- Legal forms of a companySole proprietorship and micro-enterprise, EURL, SARL, SASU, SAS and SA: number of partners, capital, liability, manager, social security scheme and taxation, then choosing the form to fit the project.
- Loans and amortization schedulesThe single-lender loan: interest computed on the outstanding balance, three repayment modes (bullet, constant principal, constant payments), the constant payment, the amortization schedule and the cost of credit.
- Management practicesThe management practices that go with agility: style matched to autonomy, servant leadership, self-organising teams, levels of delegation, visual management and continuous improvement.
- Market failuresExternalities, public goods and common resources, information asymmetries, market power: recognising each failure in a situation and choosing the instrument that corrects it.
- Milestones and indicatorsTracking a project: milestone, deliverable and task, real progress and work remaining, the S-curve, planned value, earned value, actual cost and the two performance indices.
- Mintzberg's configurationsThe five parts of an organisation, the five coordination mechanisms and Mintzberg's five configurations: recognising the key part and the mechanism of each.
- Minutes and reports of work doneMeeting minutes, decision log, official minutes and intervention report: their sections, what goes in and what stays out, and how to write actions with an owner and a deadline.
- New forms of managementFrom Taylor's directive management to theories X and Y, then management by objectives, participative and collaborative management, the liberated company, holacracy and remote work: who decides, who controls, and where it goes wrong.
- Organisational cultureThe components of culture, Schein's three levels, its functions and its limits, including the clash of cultures in a merger.
- Other agile methodsExtreme Programming, Lean applied to software, Scrumban, Crystal, FDD, DSDM and agility at scale (SAFe): the central idea of each method, what sets them apart and when to choose them.
- Performance indicators of an information systemBuilding and reading an IT department's indicators: what makes a good indicator, the balanced scorecard, usual measures (availability, time to restore, service commitments) and perverse effects.
- Porter's five forcesThe five forces that set an industry's profitability, the factors that strengthen or weaken each, and reading a fall in margins through the force at work.
- Project actors: owner and contractorWho does what in a software project: the project owner who carries the need, the budget and the acceptance, the prime contractor who builds the solution, the owner's advisor, the project manager, the steering committee and the users.
- Project life cyclesWaterfall, V-model, spiral, iterative and incremental: how each sequences its activities, its strengths and limits, the context where each fits, and the contrast between predictive and adaptive approaches.
- Project risksIdentifying a project's risks, assessing them by probability and severity, ranking them by criticality, choosing a response (avoid, reduce, transfer, accept) and keeping the risk register.
- PSM IProfessional Scrum Master I ReviewReview Scrum as described in the 2020 Scrum Guide: empiricism, values, accountabilities, events, artifacts and commitments. Enough to approach Scrum.org's PSM I knowing why each rule exists. Voyelle is not affiliated with Scrum.org. Professional Scrum Master and PSM are trademarks of their respective owners.
- Quality management and continuous improvementQuality as meeting requirements: the ISO 9001 principles, the plan-do-check-act wheel, nonconformity and the responses to it, Pareto, Ishikawa and the five whys, certification and the CMMI maturity levels.
- Reading a job postingReading a job or internship posting: its sections, required and desirable, the matching grid, the signs of a fake offer and forbidden criteria.
- Regulating responsible digital technologyThe four instruments of environmental policy and the texts that affect digital technology: planned obsolescence, the AGEC law, the REEN law, the eco-design framework, the WEEE and RoHS directives, the common charger.
- ReorganisationWhat triggers a reorganisation, its forms (restructuring, merger and acquisition, outsourcing, process reengineering, project mode), the four types of change, its impacts and the consultation of staff representatives.
- RephrasingThe four kinds of rephrasing, Porter's six attitudes and turning a vague need into a verifiable request.
- Resistance to changeWhy a user resists a new tool: causes, forms, the change curve, adoption profiles and communication responses.
- ROI, NPV, IRR: the return on an investmentFour decision criteria on a stream of cash flows: return on investment, payback period, net present value, internal rate of return; their computation, decision rule and disagreements.
- Running a meetingThe types of meeting, the three stages of a meeting (before, during, after), the roles, the facilitator's three functions and the response to five difficult participants.
- Running an innovative projectWhat sets an innovative project apart, the technology readiness scale, milestones from proof of concept to pilot, the pivot, the diffusion of innovations and its chasm, open innovation and French support schemes.
- Scrum: roles, events, artefactsScrum according to the 2020 Scrum Guide: the three accountabilities, the events and their maximum length, the artefacts and their commitment, the three pillars, and the most frequent drifts.
- Searching for documentsThe six-step method, the search tools, query operators, noise and silence, the bibliographic reference and plagiarism: finding the right documents without drowning, and saying where they come from.
- Simple and compound interestPrincipal, rate and term; simple interest (arithmetic sequence) and compound interest (geometric sequence), future value, proportional and equivalent rates, doubling time.
- StakeholdersInternal and external stakeholders, their expectations and conflicts of interest, Mendelow's power-interest matrix and the attitude to take in each box.
- Strategic alignment of the information systemThe Henderson and Venkatraman model and its four perspectives, McFarlan's grid, the IT master plan, the project portfolio weighed by value and risk, and shadow IT as a symptom.
- Structuring a reportThe fixed structure of an internship or project report: front matter, a four-step introduction, body, conclusion, bibliography and appendices, with numbered headings and captioned figures.
- Summary and document synthesisThe rules of the summary and the synthesis, the difference between them, the main idea and the example, rewording and the expected length: picking the exercise and sticking to it.
- Supporting and training peopleCommunicating, training and supporting at start-up: communication plan, training plan, key users, forms of resistance and the evaluation of a training course with Kirkpatrick's four levels.
- Sustainable development: pillars and goalsThe Brundtland definition, the three pillars, weak and strong sustainability, planetary boundaries, greenhouse gases, carbon footprint and neutrality, the sustainable development goals and the dated milestones.
- SWOT analysisInternal and external diagnosis, the four boxes of strengths, weaknesses, opportunities and threats, common sorting mistakes and crossing the boxes to choose an option.
- Taking notesThe four note-taking methods, the Cornell page, what deserves a note and what to leave out, common abbreviations and reviewing notes right after the session.
- Team performanceThe levers of collective performance (goals and indicators, motivation according to Maslow, Herzberg and Vroom, cohesion) and its pathologies: social loafing, groupthink, vague goals, untreated conflict.
- Testing and integrating a package moduleTaking a package development all the way to production: the three environments, the levels of testing, data import and its rejections, and the rollback plan.
- The 27 countries of the European UnionThe 27 member states of the European Union: each one's year of accession, from the six founders of 1957 to Croatia in 2013, and its currency, with the 21 euro area countries since Bulgaria joined in 2026.
- The Agile ManifestoThe 2001 manifesto: its four values and what stays useful on the right, its principles on delivery and pace, and what changes compared with predictive projects (adjustable scope, fixed time and cost).
- The balance sheetThe balance sheet as a snapshot of what the company owns and owes: assets and liabilities, headings, gross and net value, the equality of both sides and where profit sits.
- The break-even pointContribution margin and its rate, break-even point in value and in quantity, the date it is reached in the year, margin of safety and reading the break-even on a chart.
- The business modelWhat a business model is and the nine blocks of the Osterwalder and Pigneur canvas: customer segments, value proposition, channels, customer relationships, revenue, resources, activities, partners and costs.
- The business planThe fixed outline of the document, from its summary to the financial forecasts: forecast income statement, break-even point, cash plan, and what makes a plan credible to a bank or an investor.
- The circular economy of devicesLinear and circular economy, the waste hierarchy, electrical and electronic waste, obsolescence, refurbishment, the product-service system and the repairability index.
- The communication modelThe Shannon and Weaver model completed by feedback, Lasswell's five questions, Jakobson's six functions of language and the three families of noise: finding where a work exchange broke down and how to recover it.
- The cover letterThe application letter and email: layout, you-me-we plan, proof instead of adjectives, request for an interview and unsolicited applications.
- The CVA computing student's CV: sections, order, experience lines that show a result, posting keywords and automated screening.
- The data marketData as an economic good, how its price is formed (cost per mille, revenue per user), market concentration, and what the GDPR, the DMA, the Data Act and open public data change.
- The decision-support chainThe path of a figure from the operation to the decision-maker: sources, extraction and transformation, warehouse, data marts, reporting. What sets transaction processing apart from analysis, and who uses what.
- The digitalisation of the companyDigitising, digitalising, transforming: the three degrees, the levers of digital technology, its effects on the functions of a company and its risks, from a badly copied process to digital exclusion.
- The environment: PESTEL analysisThe macro-environment and the micro-environment, the six dimensions of PESTEL, and reading the same factor as an opportunity or a threat depending on the organisation.
- The environmental footprint of digital technologyThe three tiers and four life-cycle phases, the four indicators, life-cycle assessment and the functional unit, embodied energy, the rebound effect and burden shifting.
- The environmental impact of an information systemThe footprint of an organisation's information system: manufacturing versus use, the scopes of a greenhouse gas inventory, a data centre's PUE, the levers of an IT department and the AGEC and REEN laws.
- The ERPWhat makes an enterprise resource planning system: a single database, modules by function, one entry whose effect spreads, a standard supplied by a vendor. Its strengths and limits against siloed applications, custom development and linked specialist software, hosted in-house or rented online.
- The ethics of storing dataThe questions raised by any data that is kept: whether to collect it, for how long, in what form, where and at what cost. Minimisation, purpose, retention period, anonymisation and pseudonymisation, dormant data and location.
- The fact-finding interviewRunning an interview with a client or a user: the three forms, the guide, the five stages, the funnel, the types of questions and the mistakes to avoid.
- The financing planA start-up's lasting needs and resources, working capital requirement, self-financing capacity, the three-year plan, and what each source of funding asks for in return.
- The four dimensions of an information systemThe informational, technological, organisational and human dimensions through which an information system, and a project that changes it, is read, and what happens when a project deals with only one.
- The full cost of an information systemWhat an IT service really costs over its lifetime: total cost of ownership, capital and operating expenditure, direct and indirect costs, allocation keys, hidden costs and internal chargeback to the user departments.
- The functions of a companyFayol's six functions and their present-day form, operational functions versus support functions, and the five verbs of the administrative function.
- The human resources processesThe five processes of a human resources information system, the path of a payroll run, and access to employee data.
- The income statementThe income statement as a film of the year: expenses and revenue, operating, financial and exceptional results, and the gap between profit and cash.
- The job interviewBefore, during, after: interview forms, the two-minute introduction, the STAR method, tricky questions, forbidden questions, thank-you and follow-up.
- The management dashboardObjective, indicator, target, variance and alert threshold: choosing the right indicators, computing a variance, reading a dashboard and tracing a variance back to its cause.
- The manager's skillsMintzberg's ten roles, Katz's skills, the Blake and Mouton grid, Hersey and Blanchard's situational leadership and delegation: what a manager does, must know, how they lead and what they can hand over.
- The market: supply, demand and priceThe law of supply and demand, the equilibrium price, shortage and surplus, shifts of a curve, price elasticity and the four market structures.
- The network organisationRefocusing on the core business and coordinating partners: outsourcing, subcontracting, franchising, alliance, joint venture, the make-or-buy trade-off, and the risks of dependence.
- The oral defencePreparing and delivering the defence of an internship or a project: the two parts, the plan of the talk, the slides, the timing, the demonstration and its fallback, answering the jury.
- The outline of a requirements specificationThe sections of a requirements specification and their order: context and objectives, scope, existing situation, functional needs, non-functional requirements, constraints, schedule, budget and acceptance criteria.
- The phases of a projectThe course of a project in a classic life cycle: feasibility, scoping, design, build, acceptance, deployment and closure, with each phase's purpose, deliverable and exit milestone.
- The production chain: bill of materials, requirements and stockBill of materials and routing, production order, push and pull flow, net requirements, safety stock, reorder point and just-in-time.
- The professional emailThe parts of an email, To, Cc and Bcc, the subject line, the greeting, the signature, replying, replying to all or forwarding, and the usual mistakes: writing a message that is understood and can be found again.
- The professional networkGetting known and getting help: strong and weak ties, the hidden market and referrals, the circles to approach, the online profile, the outreach message, the informational interview and keeping the network alive.
- The purchasing and sales processesThe two mirror chains of documents, from purchase request to supplier payment and from quote to cash collection: what each document changes and the controls that prevent disputes.
- The risks of an information systemRisks as seen by the one who steers: families, the four criteria affected, the probability and impact map, four treatments, risk owner and dependence on a supplier.
- The steps to start a companyFrom the idea to registration: market study, articles of association, capital deposit, legal notice, one-stop shop, SIREN and SIRET numbers, Kbis extract, and the body that handles each formality.
- The survey questionnaireBuilding and analysing a questionnaire: structure, question forms, defects to avoid, response rate, simple and cross tabulation.
- The tech job marketReading the market before applying: job offers and job seekers, shortage occupations, open and hidden markets, sources and indicators, from gross to net.
- The value chainThe nine activities of Porter's value chain, primary and support, the margin, and using the chain to find where competitive advantage comes from.
- Tracking boards and chartsThe tracking tools visible to the whole team: task board, burndown, burnup, velocity chart; reading their shape and what it says about the sprint.
- Training usersPreparing and running a hands-on session: observable objective, methods, running order, materials, checking understanding and evaluation.
- Types and sizes of organisationsThe four families of organisations, the three sectors of activity and the four size categories of the 2008 French decree with their thresholds for headcount, turnover and balance sheet.
- Types and strategy of innovationWhat innovation is about (product, process, organisation, marketing), its intensity, its origin, its diffusion (Rogers' adopter categories, the S-curve) and the pioneer and follower strategies.
- Types of costsThe three ways of classifying a cost: direct or indirect with respect to a product, fixed or variable with respect to activity, includable, non-includable or notional; mixed costs and how to split out their fixed part.
- Unemployment: measuring and understanding itThe ILO definition of the unemployed, the labour force, unemployment, employment and activity rates, the halo and underemployment, and the three forms of unemployment with the policy that answers each.
- VAT: output, input and payableHow VAT works: excluding and including tax, French rates, output and input VAT, the payable balance or credit, and neutrality for the company.
- Verbal and non-verbal communicationThe three channels of a face-to-face message (verbal, paraverbal, non-verbal), language registers, Hall's four distances, congruence between channels and what Mehrabian's rule really measures.
- Virtual money and online paymentThe functions of money and its forms, then online card payment: the actors, authorisation, strong authentication, clearing and settlement, fees and disputed payments.
- Virtualisation as a lever on consumptionWhy virtualising cuts consumption: utilisation, idle power, consolidation, ghost servers, pooling, PUE, and the limits of virtualisation (sprawl, oversizing, rebound).
- Visual communicationComposing a slide, a poster or a report page: contrast, repetition, alignment, proximity, visual hierarchy, typography, colour and one idea per slide.
- What an information system is forThe information system set apart from the IT system, its five resources and four functions, its place between steering and operations, the three decision levels it serves, its four stakes and the role of the IT department.
- What an organisation is forWhat an organisation is, what it is for, the chain from purpose to objectives to means, the SMART objective and the three measures of performance: effectiveness, efficiency, relevance.
- What responsible digital technology costs and savesThe economics of a reduction decision: total cost of ownership, annual cost by period of use, payback period, externalities, internal carbon price and responsible purchasing.
- Who's who in the data economyThe data value chain in five links and the players in each: producers, platforms, brokers, hosting providers, advertisers, regulators.
- Workforce and skills planningThe five-step approach, from the state of resources to the action plan, its tools (job description, skills framework, age pyramid, career review) and the duty to negotiate in large companies.
- Working capital, working capital requirement and cashThe functional balance sheet and its three quantities: net working capital, working capital requirement and net cash, and the effect of customer, supplier and stock lead times.
- Writing technical documentationWriting a procedure that can be followed without guessing: the reader, prerequisites before the steps, one action per step, the expected result, the warning before the action and one word per thing.
Health and medicine
- Adaptations to trainingWhat endurance and strength change in the heart, blood, muscle and nervous system.
- Agonist, antagonist, synergist and fixatorThe roles a muscle plays in a movement, agonist-antagonist pairs and contraction modes.
- Anatomical terminologyThe shared language of anatomy: the reference position, the three planes and the terms of direction (medial, lateral, proximal, distal, cranial, caudal, ventral, dorsal…), to place any structure without ambiguity.
- Anatomy — Bones of the skeletonRecognise and locate every bone of the skeleton on a 3D model you can turn: skull, spine, thorax, limbs, hands and feet. For each bone, one card to name it and one card to point to it. 3D model: BodyParts3D, © The Database Center for Life Science, licensed under CC BY 4.0.
- Antibiotic familiesThe main antibiotic families, their target, side effects and precautions (beta-lactams, aminoglycosides, macrolides, fluoroquinolones, glycopeptides, tetracyclines, sulfonamides, nitroimidazoles), bacterial resistance and the rules of good use.
- AntidotesThe reference emergency antidotes, each with its poison: N-acetylcysteine, naloxone, flumazenil, vitamin K, protamine, oxygen, atropine, hydroxocobalamin, fomepizole, digoxin antibody fragments, glucagon and glucose, with the situations that call for them.
- Balance and postureCentre of mass, base of support and three sources of information: vision, vestibule and proprioception.
- Blood pressure and its regulationWhat blood pressure measures, what makes it vary (output and resistance), how the body regulates it within seconds (baroreflex) and within hours (kidney, renin-angiotensin-aldosterone system), and what happens when it rises or collapses.
- Blood, haemostasis and blood groupsWhat blood contains and what a blood count says, how bleeding stops (primary haemostasis, coagulation, fibrinolysis), the ABO and Rhesus groups and the compatibility rules of transfusion.
- BreathingFrom air to tissues: the mechanics of ventilation and its volumes, dead space, exchanges in the alveoli, the transport of oxygen and carbon dioxide in blood, and the control of breathing, with the situations where it goes wrong.
- Carbohydrate and fat oxidationThe aerobic system, respiratory quotient, the crossover concept and the intensity of peak fat oxidation.
- Clinical scales and scoresThe scores carers calculate at the bedside: Glasgow, pain scales (NRS, VAS, Algoplus), Braden and Norton for pressure ulcers, Apgar, MMSE, BMI and qSOFA, with cases to score.
- Contraction modesConcentric, eccentric, isometric, plyometric and isokinetic: what the muscle does and what it costs.
- Digestion and absorptionThe path of food from mouth to rectum, what each segment secretes and absorbs (saliva, gastric acid, bile, pancreatic juice), the hormones that orchestrate digestion, and the diseases that reveal each step.
- Dose calculationThe nurse's calculations: unit conversions, percentage concentrations, the rule of three, weight-based doses, infusion rates in mL/h and drops per minute, syringe pumps and insulin, with prescriptions to work out and the traps behind errors.
- Drug name stemsRecognising a drug's class from its name: sixteen stems of the international non-proprietary names of the classes in the programme (-olol, -pril, -sartan, -statin, -prazole, -cillin, -floxacin, -mab, -tinib…), with their examples and traps.
- Eating before, during and after exerciseThe pre-exercise meal, carbohydrate and water during long efforts, and restoring stores afterwards.
- Excitation-contraction couplingFrom the motor neuron's action potential to filament sliding, then relaxation.
- Exercise at altitude and underwaterOxygen pressure at altitude, acclimatisation, training strategies; pressure underwater, Boyle's law and decompression.
- Exercise physiologyWhat happens in the body during exercise: the three energy systems that supply ATP and how long they last, VO₂max and thresholds, muscle fibre types, how the heart and breathing adapt, and what training changes.
- Force-velocity and force-length relationsThe faster muscle shortens, the less force it produces; force also depends on length; power peaks in between.
- Glycolysis and lactateAnaerobic glycolysis, what becomes of lactate, lactate thresholds and what training changes.
- Health indicatorsMeasuring a population's health: prevalence and incidence, mortality, infant and premature mortality, case fatality, morbidity, life expectancy and healthy life expectancy, with cases to stop mixing them up.
- Hormones and their glandsOne hormone per main endocrine gland: the hypothalamus and pituitary, the thyroid, the parathyroids, the adrenals and the pancreas, what each hormone does, how feedback regulates it, and the diseases of excess or lack.
- Hormones of exerciseCatecholamines, insulin, glucagon, cortisol, growth hormone, ADH and aldosterone during exercise.
- ImmunityHow the body defends itself: innate immunity and inflammation, adaptive immunity with its B and T lymphocytes, the antibody classes, the memory that vaccination relies on, and what happens when defence is lacking, overreacts or targets the wrong thing.
- Joints and movementsHow bones join: fibrous, cartilaginous and synovial joints, the six shapes of synovial joints and their examples, what a joint is made of, and the words for movements (flexion, abduction, pronation, circumduction…).
- Landmark health lawsThe laws framing care in France: patients' rights (Kouchner, 2002), end of life (Leonetti, 2005; Claeys-Leonetti, 2016), abortion (Veil, 1975, time limit extended in 2022, freedom written into the Constitution in 2024), bioethics (2021), psychiatric care without consent (2011) and the Évin law (1991).
- Micro-organismsBacteria, viruses, fungi and parasites: what sets them apart, Gram staining and bacterial shapes, colonisation and infection, multidrug-resistant bacteria and spores, and healthcare-associated infections.
- Micronutrients and hydrationIron, calcium, vitamin D, B vitamins, sweat sodium and the dehydration level that hurts performance.
- Motor areas, cerebellum and basal gangliaPrimary motor cortex, premotor cortex, supplementary motor area, cerebellum and basal ganglia: who plans, launches and adjusts movement.
- Motor units and recruitmentMotor units, Henneman's size principle, recruitment and firing rate: how muscle grades its force.
- Muscle fibre typesSlow oxidative type I, fast oxidative-glycolytic IIa and fast glycolytic IIx fibres: properties and sports.
- Normal vital signsThe normal values of vital signs in adults and newborns (heart and breathing rate, blood pressure, temperature, saturation, urine output, capillary glucose), the words for abnormalities, and the situations where they must raise the alarm.
- Oxygen deficit and EPOCVO2 lagging at the start of exercise, what covers the gap, and the consumption that stays high afterwards.
- Oxygen transportHaemoglobin, the dissociation curve, the Bohr effect and the arteriovenous difference in exercise.
- Palpable bony landmarksAcromion, epicondyles, olecranon, iliac spines, greater trochanter, tibial tuberosity, malleoli, C7: the bony reliefs felt under the skin that are used to measure, locate and mark.
- PharmacokineticsWhat the body does to a drug: absorption, bioavailability and hepatic first pass, distribution and protein binding, liver metabolism and interactions, renal elimination, half-life and steady state, with the situations where the dose must be adjusted.
- Professional secrecy and consentThe rules that protect the patient: professional secrecy and its penalties, secrecy shared within the care team, the exceptions set by law, information and free, informed consent, refusing care, minors and protected adults, and emergencies.
- ProprioceptionMuscle spindles, Golgi tendon organs, joint receptors and the vestibule: knowing where the body is without looking.
- Receptors, agonists and antagonistsWhat the drug does to the body: binding to a receptor, agonists, partial agonists and antagonists, affinity, efficacy and potency, the therapeutic index, the main adrenergic and muscarinic receptors, tolerance, and the antagonists used as antidotes.
- Skeletal striated muscleFrom fibre to sarcomere: myofibrils, actin, myosin, sarcoplasmic reticulum and sliding filaments.
- Spinal curves and postureLordoses and kyphoses, sagittal balance, scoliosis, hyperkyphosis and hyperlordosis: why a curved spine resists better.
- Spinal reflexesThe reflex arc, stretch reflex, inverse stretch reflex, flexion and crossed extension: the responses the cord gives on its own.
- Standard and additional precautionsThe hygiene rules of care: standard precautions for every patient, hand hygiene, gloves and dress, additional contact, droplet and airborne precautions (surgical or FFP2 mask), and what to do after a blood exposure accident.
- The 12 cranial nervesThe 12 cranial nerves, from I to XII: the name of each number, the number of each name, then the nerve behind each function. On the back, whether it is sensory, motor or mixed.
- The ankle and the footThe talocrural, subtalar and midtarsal joints, the arches of the foot, lateral ligaments and sprains, movements and ranges.
- The athlete's macronutrientsCarbohydrate, fat, protein: energy, role and the athlete's needs by training load.
- The ATP-PCr systemATP and phosphocreatine stores, creatine kinase, immediate power and recovery time.
- The brachial and lumbosacral plexusesThe nerve networks of the limbs: the roots, trunks and cords of the brachial plexus and its five terminal branches, the femoral, obturator and sciatic nerves, what each controls and what its injury causes (wrist drop, carpal tunnel, foot drop…).
- The brain: lobes and structuresThe lobes of the brain and their functions, the language areas, the grooves that separate them, the deep structures (thalamus, hypothalamus, corpus callosum), the cerebellum, the brainstem, the meninges and the cerebrospinal fluid, and the deficits a lesion of each causes.
- The cardiac cycle and the ECGHow the heart beats: the conduction system, systole and diastole with their sounds, cardiac output, and reading the waves of the electrocardiogram up to the most common abnormalities.
- The elbow and the wristHumero-ulnar, humeroradial and radio-ulnar joints, the radiocarpal joint: flexion, extension, pronation, supination and deviations.
- The French health systemWho does what in French healthcare: national health insurance and supplementary cover, the coordinated care pathway and the GP, regional health agencies, HAS, ANSM and Santé publique France, mother and child protection, hospitals and the funding voted each year.
- The great arteries and veinsThe aorta from the aortic valve to its bifurcation and its direct branches, the venae cavae and their direct tributaries, and the portal vein: what each vessel supplies or drains, at which level, and what clinical practice draws from it.
- The hand and its jointsCarpus, metacarpus and phalanges, the thumb's trapeziometacarpal joint, opposition, grips and the arches of the hand.
- The heart: chambers, valves and coronariesThe anatomy of the heart: the four chambers and what enters and leaves them, the four valves, the septum, the pericardium, the coronary arteries and their territories, and what clinical practice draws from them (infarction, murmur, tamponade).
- The heart's response to exerciseHeart rate, stroke volume, cardiac output, estimated maximal heart rate and cardiac drift.
- The hip jointThe hip joint: femoral head, acetabulum, labrum, ligaments, movements, ranges and its role in weight-bearing.
- The kidney and fluid and electrolyte balanceHow the kidney makes urine and keeps the body in balance: the nephron and the path of urine, filtration, reabsorption and secretion, the hormones that control them (ADH, aldosterone), how kidney function is measured and what its decline causes.
- The knee jointTibiofemoral and patellofemoral joints, menisci, cruciate and collateral ligaments, movements and sports injuries.
- The main drug classesThe classes of the IFSI pharmacology unit, each with its effect and major side effects: painkillers (paracetamol, NSAIDs, opioids), anticoagulants and antiplatelets, diuretics, antihypertensives, corticosteroids, insulin, benzodiazepines, and what the carer monitors.
- The muscles of the arm and forearmElbow flexors and extensors, pronators and supinators, wrist flexors and extensors.
- The muscles of the hip and buttockIliopsoas, gluteals, tensor fasciae latae, piriformis, adductors and sartorius: hip flexion, extension, abduction, adduction and rotations.
- The muscles of the leg and footTriceps surae, tibialis anterior, tibialis posterior, fibulars and long toe muscles: plantarflexion, dorsiflexion, inversion and eversion.
- The muscles of the shoulder and shoulder girdleTrapezius, rhomboids, serratus anterior, deltoid, pectoralis major and the rotator cuff: what moves the scapula, what moves the arm.
- The muscles of the thighQuadriceps and hamstrings: the four heads that extend the knee, the three muscles that flex it and extend the hip.
- The muscles of the trunk and neckSternocleidomastoid, erector spinae, abdominals, latissimus dorsi and diaphragm: holding, turning and breathing.
- The nerves of the limbsThe terminal nerves of the brachial and lumbosacral plexuses, the muscles they control and what damage to them reveals.
- The neuron and the synapseHow a neuron passes a message: the resting and action potentials, conduction along the axon and the role of myelin, the chemical synapse and its neurotransmitters, and what toxins, drugs and diseases change there.
- The shoulder jointThe glenohumeral joint and the shoulder complex: surfaces, capsule, labrum, ligaments, movements and ranges.
- The spinal cordGrey and white matter, horns, roots, ascending and descending tracts: the cord relays and integrates movement.
- The spine in motionThe intervertebral disc, facet joints, movements by level, the atlanto-axial joint and the loads on the lumbar spine.
- The vaccination scheduleVaccination in France according to the current schedule: live and inactivated vaccines, compulsory infant vaccinations, MMR, adult boosters, HPV, flu, whooping cough in pregnancy, contraindications, and herd immunity. The schedule changes every year: this deck is reviewed at each new edition.
- The vertebrae and the spineThe spine from the neck to the coccyx: the regions and their vertebrae, the typical vertebra, the atlas and the axis, the discs and the curves, what clinical practice draws from them (lumbar puncture, disc herniation, scoliosis), and the landmark vertebrae to touch on the skeleton.
- Thermoregulation in exerciseHeat produced by muscle, ways of losing it, sweating, heatstroke and acclimatisation.
- Usual laboratory valuesThe usual values of the most prescribed adult tests (blood count, electrolytes, kidney function, glucose, liver tests, inflammation, clotting, blood gases) and what an abnormality should suggest. Ranges vary slightly between laboratories: always refer to those on the report.
- Ventilation and ventilatory thresholdsMinute ventilation, tidal volume and rate, first and second thresholds, VO2max.
- Vision and reaction timeCentral and peripheral vision, simple and choice reaction time, what lengthens and shortens it.
History and geography
- Capitals of the worldThe capital of every country, continent by continent: the 193 member states of the UN, its two observer states (Palestine and the Holy See), Taiwan and Kosovo. For each country, one card from the country to its capital and one from the capital to its country. Special cases (several capitals, a government seated elsewhere, a disputed status) are explained on the back. Country names follow UN usage.
- Countries of AfricaPlace the 54 countries of Africa on the map, framed on the continent. For each country, one card to show it on the map (the first tap counts) and one to recognise it when it is highlighted; the answer also gives its capital. Microstates and small islands have a round target. Country names follow UN usage.
- Countries of AsiaPlace the 48 countries of Asia on the map, framed on the continent. For each country, one card to show it on the map (the first tap counts) and one to recognise it when it is highlighted; the answer also gives its capital. Microstates and small islands have a round target. Country names follow UN usage.
- Countries of EuropePlace the 46 countries of Europe on the map, framed on the continent. For each country, one card to show it on the map (the first tap counts) and one to recognise it when it is highlighted; the answer also gives its capital. Microstates and small islands have a round target. Country names follow UN usage.
- Countries of OceaniaPlace the 14 countries of Oceania on the map, framed on the continent. For each country, one card to show it on the map (the first tap counts) and one to recognise it when it is highlighted; the answer also gives its capital. Microstates and small islands have a round target. Country names follow UN usage.
- Countries of the AmericasPlace the 35 countries of the Americas on the map, framed on the continent. For each country, one card to show it on the map (the first tap counts) and one to recognise it when it is highlighted; the answer also gives its capital. Microstates and small islands have a round target. Country names follow UN usage.
- Countries of the worldPlace every country on the world map, continent by continent: the 193 member states of the UN, its two observer states (Palestine and the Holy See), Taiwan and Kosovo. For each country, one card to show it on the map (the first tap counts) and one to recognise it when it is highlighted; the answer also gives its capital. Microstates and small islands have a round target. Country names follow UN usage.
- Flags of the worldRecognise the flag of every country, continent by continent: the 193 member states of the UN, its two observer states (Palestine and the Holy See), Taiwan and Kosovo. For each country, one card to pick it among four names with close flags, and one card to recall its flag. Country names follow UN usage.
- French départementsThe 101 départements, region by region: the 96 of metropolitan France (Corse-du-Sud and Haute-Corse included) and the 5 overseas ones, in insets. For each département, one card to show it on the map (the first tap counts) and one to recognise it when it is highlighted; the answer gives its name, number and prefecture. Paris and its inner suburbs have an enlarged inset.
- Key dates in French historyThe 52 dates to know, from Alesia (52 BC) to the euro (2002), period by period: the date of each event. Also on the Explorer's timeline, with the dynasties and regimes.
- Presidents of the French Fifth RepublicThe Presidents of the French Fifth Republic in order, from Charles de Gaulle to Emmanuel Macron, and the dates of their terms. On the back, a landmark of each presidency.
- Presidents of the United StatesThe 47 presidencies of the United States in order, from George Washington to Donald Trump. Grover Cleveland and Donald Trump, each President for two non-consecutive terms, count as two numbers each.
- The 50 US statesPlace the 50 states of the United States on the map, region by region (Northeast, Midwest, South, West), Alaska and Hawaii in insets. For each state, one card to show it on the map (the first tap counts) and one to recognise it when it is highlighted; the answer also gives its capital.
Languages
- Business vocabulary in EnglishThe English words of the company: its departments, its people, its money, life at work, and the false friends that trap French speakers (training, internship, deadline, profit, to attend).
- CV and cover letter in EnglishThe layout of a CV and a cover letter in English, what goes in and what stays out, action verbs, the equivalents of French qualifications and language levels.
- Debating tech ethics in EnglishThe vocabulary of ten tech debates, the structure of an argument, degrees of certainty and six fallacies named in English.
- Describing a chart in EnglishThe words for charts, verbs and adverbs of change, prepositions before a figure, approximations, reading numbers the English way and the plan of a commentary.
- Écrire une documentation technique en anglaisLe plan d'un README, les règles du style technique, la docstring et les fautes que font les francophones : articles, noms indénombrables, allow to, prépositions, ordre des mots.
- German irregular verbsThe 138 German strong and mixed verbs worth knowing, from the most common to the rarest: the 50 essentials, the next 50, then the advanced ones. On the front, the verb in English; on the back, its principal parts: infinitive, third person singular present, preterite and past participle with its auxiliary. New cards come in order of frequency: sein, haben and werden first.
- Giving a presentation in EnglishThe structure of a talk and its signposting phrases, answers to questions, slide rules and the word stress of technical words French speakers often misplace.
- Hangul, the Korean alphabetThe 40 letters (jamo) of hangul: 14 basic consonants, 5 double ones, 10 basic vowels and 11 compound ones. The letter on the front, its official romanisation (Revised, 2000) on the back, with the sound changes at the end of a syllable.
- HiraganaThe 104 hiragana, the first script you learn in Japanese: the 46 basic ones, the voiced sounds (with ゛ and ゜) and the combined sounds. The character on the front, its reading in rōmaji (Hepburn) on the back, with its katakana counterpart.
- Intercultural skillsHofstede's dimensions, context and time according to Hall, the difference between a stereotype and a generalisation, British understatement and the gaps between British and American English.
- KatakanaThe 104 katakana, the Japanese script for foreign words, onomatopoeia and brand names: the 46 basic ones, the voiced sounds (with ゛ and ゜) and the combined sounds. The character on the front, its reading in rōmaji (Hepburn) on the back, with its hiragana counterpart.
- L'anglais de la bureautiqueLes touches du clavier, le traitement de texte, le tableur, le diaporama et les actions sur les fichiers, avec les noms anglais des fonctions de tableur.
- L'anglais des donnéesLes mots anglais de la base de données et de l'analyse, les bornes d'une demande de données (at least, up to, fewer than, all but) et les noms qui ne se comptent pas.
- L'anglais des réseaux et de la sécuritéLes mots anglais du réseau et de la sécurité, les paires que le français confond, les messages de diagnostic des outils réseau et les formules d'un avis de sécurité.
- L'anglais des systèmes d'informationLes mots anglais du système d'information, ses sigles et leurs équivalents français, et les formules des annonces d'un fournisseur (maintenance, end of life, sunset).
- L'anglais du corps et de l'entraînementLes mots anglais du corps, des blessures, de l'entraînement et des terrains pour lire, coacher et arbitrer.
- L'anglais du développementLes mots anglais du dépôt, des tickets, des tests, de la livraison et de la revue de code, les six rubriques d'un changelog et le sujet de commit à l'impératif.
- L'anglais du logiciel et du codeLes mots anglais des familles de logiciels et de la programmation, le nom des signes d'un code et la lecture des messages d'erreur du terminal et des interpréteurs.
- L'anglais du matérielLes mots anglais des composants, des périphériques, de la connectique, des appareils, des unités et des gestes du matériel : nommer ce qu'on branche, ce qu'on remplace et ce qu'une fiche technique annonce.
- Les métiers du numérique en anglaisLes intitulés de poste du numérique, ce que fait chacun, les niveaux d'expérience, les mots du contrat et ceux d'une offre d'emploi en anglais.
- Lire un article scientifique en anglaisLe vocabulaire d'un article de sciences du sport en anglais : structure IMRaD, méthodes, statistiques et conclusions.
- Lire un cahier des charges en anglaisLe plan d'un cahier des charges en anglais, les mots-clés d'exigence de la RFC 2119, les récits utilisateurs, les critères d'acceptation, les bornes chiffrées et les mots du contrat.
- Lire une documentation en anglaisLes rubriques d'une entrée de référence et d'une page de manuel, les marqueurs qui changent le sens d'une phrase, les abréviations, les groupes nominaux empilés et les faux amis de la documentation.
- Meetings and phone calls in EnglishThe stages of a meeting and its vocabulary, phrases for agreeing, disagreeing, interrupting and asking for clarification, the lines of a phone call, spelling out an address and softeners.
- Morse codeThe 26 letters and 10 digits of international Morse code, both ways: write each sign in dots and dashes, then read it back. Letters come from the shortest to the longest (E, T, I, A, N, M…), as in the Morse tree.
- Negotiation and conflict in EnglishThe stages of a negotiation and their phrases, the key notions, principled negotiation, bargaining conditionals, the five Thomas-Kilmann modes and phrases for defusing tension.
- Suivre un tutoriel en anglaisLe plan d'un tutoriel, les verbes de consigne, les mots qui ordonnent ou posent une condition, les modaux d'obligation et leur piège, et les conventions de substitution.
- Teamwork in EnglishThe words of team life, the daily stand-up and its verb tenses, the phrases for helping, delegating and giving feedback, and the abbreviations of team chat.
- The Cyrillic alphabetThe 33 letters of the Russian alphabet, upper and lower case, with their sound in English transcription. The false friends (В, Н, Р, С, У, Х), which look like Latin letters but read differently, are flagged on the back.
- The Greek alphabetThe 24 letters of the Greek alphabet, upper and lower case, both ways: recognise them and write them. On the back, what each letter stands for in mathematics and physics (π, Δ, Σ, λ, μ, Ω…).
- The job interview in EnglishThe classic interview questions and what they look for, the STAR method, the tenses for telling your story and the phrases for asking people to repeat or buying time.
- The NATO phonetic alphabetThe 26 words of the international radiotelephony alphabet (Alfa, Bravo, Charlie…), both ways: spell a letter, then find the letter of a word. Spelling follows ICAO (Alfa, Juliett).
- The professional e-mail in EnglishThe layout of an e-mail, the three registers and their greeting and sign-off pairs, set phrases by function, abbreviations, dates and deadlines, and the classic mistakes French speakers make.
- Verbes irréguliers anglaisLes 174 verbes irréguliers anglais à connaître, classés du plus courant au plus rare : les 50 essentiels, ceux du collège, puis ceux du lycée et au-delà. Au recto, le verbe en français ; au verso, sa base verbale, son prétérit et son participe passé, avec les variantes britanniques et américaines. Les nouvelles cartes arrivent dans l'ordre de fréquence : be, have et do d'abord.
- Video calls in EnglishThe words of the tool, the phrases for technical problems, the ones that run a session, the verbs that move an appointment and telling the time across time zones.
- Writing minutes and reports in EnglishMeeting minutes and the short report, reporting verbs, reported speech, the impersonal passive style, linking words and recommendations.
Law
- Best-efforts, result and advice obligationsThe three obligations of an IT provider: best efforts, result and advice. Who must prove what, how to recognise them in a clause, and the customer's duty to cooperate.
- Burden and means of proofWho proves, what and how: the burden of proof, presumptions, the five means of proof, free proof and written proof, and the fairness of evidence.
- Civil liabilityMaking good a harm: contractual and tort liability, the three conditions, the types of damage, full compensation and the grounds for exoneration.
- Clauses in an employment contractThe clauses common in IT: non-competition, confidentiality, exclusivity, mobility, training repayment and ownership of creations, with their conditions of validity and what happens to an invalid clause.
- Clauses in IT contractsThe clauses that matter in an IT contract (acceptance, service levels, penalties, limitation of liability, intellectual property, reversibility) and the two legal limits of articles 1170 and 1171 of the Civil Code.
- Compliance documentationTen documents that prove a service follows the law: what each is for, who it addresses, who writes it and which event requires an update.
- Copyright and related rightsLiterary and artistic property outside software: the work of authorship, works by several people, moral and economic rights, exceptions, the public domain, assignment and related rights.
- Copyright in softwareThe special regime for software: what is protected and what stays free, originality, ownership between employer, employee, intern and freelancer, duration, the reduced moral right, the user's rights and filing as proof.
- Criminal law of the digital worldThe offences of the Godfrain act, identity theft, phishing, their penalties, attempt, and what makes a security test lawful.
- Criminal liabilityPunishing an offence: how it differs from civil liability, legality of offences and penalties, the three elements, classification into petty offence, misdemeanour and felony, attempt and legal persons.
- Data subjects' rightsThe eight rights the GDPR gives to individuals: their conditions, their limits, the one-month deadline to answer, the absence of charge and the complaint to the CNIL. Recognising the request and deciding what follows.
- Digital evidenceWhat a digital item is worth before a judge: electronic writing, electronic signature, reliable copy, e-mail, screenshot, connection log, bailiff's report, hash and timestamp.
- Digital sovereignty and data transfersWho has authority over data: laws with extraterritorial reach, transfers outside the Union under the GDPR, the Schrems rulings, the 2023 framework with the United States and European answers such as SecNumCloud.
- Employee freedoms and monitoringWhat the employer may monitor: proportionality, the prerequisites of a system, email and files, browsing, video surveillance, geolocation, biometrics, personal devices, the IT charter, the system administrator and social media.
- Employee protectionHow statute, collective agreement and contract fit together, working time and overtime, the right to withdraw and to disconnect, non-discrimination, dismissal procedure and remedies.
- Forming a valid contractFrom first exchange to agreement: negotiation, offer and acceptance, validity conditions, defects of consent, nullity and the classifications of contracts.
- Free and open-source licencesThe freedoms of free software, the difference from freeware and the public domain, the main licence families (permissive, weak and strong copyleft, AGPL), their obligations, SPDX identifiers and Creative Commons licences.
- How Europe regulates digital technologySix recent texts and what each one governs: digital markets, digital services, data governance, the Data Act, artificial intelligence and the French law of 21 May 2024.
- Information security: legal dutiesWhat the law requires on security: appropriate measures, breach notification, NIS 2, DORA, the ANSSI, sector regimes, the complaint for the insurer and management liability.
- Key articles of the French ConstitutionThe 22 most cited articles of the French Fifth Republic's Constitution, from article 1 to 89: the President (5, 6, 8, 12, 16), the Government (20, 49 and the “49.3”), statute and regulation (34, 37, 38), the Constitutional Council and the QPC (56, 61, 61-1). Both ways.
- Lawful bases for processingThe six grounds of article 6, the qualities of valid consent and its withdrawal, the rule on trackers and what the choice of ground entails: justifying a processing operation and spotting consent that is worth nothing.
- Online evidence and electronic signaturesProving a commitment made online: the three eIDAS signature levels, timestamping, qualified trust service providers, evidence agreements and the evidence file for a consent.
- Online selling: the seller's dutiesWhat an online shop owes its consumers: legal notices, pre-order information, the order flow, the 14-day withdrawal right, delivery, the legal guarantee of conformity and e-mail marketing.
- PatentsThe conditions for patentability, the exclusions and the case of computer-implemented inventions, filing, publication, duration, the priority period and the three regimes for employee inventions.
- Performing and breaching a contractWhat a contract imposes, the five remedies for breach, formal notice, force majeure, the penalty clause and the five-year limitation period.
- Personal data, processing and the scope of the GDPRThe definitions of article 4 of the GDPR, the special categories of data, the difference between pseudonymising and anonymising, and when the regulation applies or not: classifying a piece of data, an actor and a processing operation.
- Protecting databasesThe twofold protection of a database: copyright in an original structure, the producer's right over content that results from substantial investment; duration, forbidden acts, exceptions, scraping and open data.
- Sources of law and the hierarchy of normsThe texts and decisions from which a rule of law comes, their rank in the pyramid of norms, who writes them, the reviews that sanction a lower text and how a statute applies over time.
- The branches of lawThe difference between objective law and subjective rights, the line between public and private law, the main branches, property and non-property rights and the two kinds of persons.
- The CNIL: duties, inspections and penaltiesThe French data protection authority: its duties, its inspections, the procedure leading to a penalty, the scale of fines and the European one-stop shop.
- The controller's obligationsWhat the controller must be able to show: the register of processing, protection by design and by default, the processor contract, the impact assessment and the data protection officer.
- The court systemThe two orders of courts and their three levels, the competent court for each dispute, the role of the supreme and European courts and what cassation decides.
- The employment contract: forms and terminationThe three criteria of an employment contract, what separates it from an internship and from freelance work, permanent, fixed-term, temping and apprenticeship contracts, the probation period, and the three ways to end a permanent contract with their effects.
- The GDPR principlesThe seven principles of article 5: what each one forbids, the measure that respects it and the reference retention periods, so as to recognise the principle a practice violates.
- The map of intellectual propertyThe two branches of intellectual property and its six protections: what each one protects, how the right comes into being, how long it lasts, what stays free, trade secrets and infringement.
- The status of online intermediariesWho answers for online content: publisher and intermediaries, the host's limited liability, notice and action, and the Digital Services Act duties by service size.
- Trademarks, designs and domain namesThe conditions for a valid trademark, filing by Nice class, duration and revocation, protecting an appearance through design rights, and domain name allocation in the face of trademarks.
- Types of IT contractThe eight IT contracts (licence, bespoke development, integration, maintenance, outsourcing, hosting, online service, technical assistance), the two pricing modes, fixed price and time and materials, and the risk of unlawful labour lending.
Life sciences
- Carbohydrates and lipidsThe big molecules of energy and structure: monosaccharides, disaccharides and polysaccharides (starch, glycogen, cellulose), saturated and unsaturated fatty acids, triglycerides, phospholipids, cholesterol and lipoproteins, and what nutrition makes of them.
- Cell signalling and apoptosisHow cells talk to each other: ligands and receptors, the main receptor families, second messengers and signal amplification, then how a cell dies cleanly (apoptosis) or by accident (necrosis), and what diseases and drugs make of it.
- Connective tissue, cartilage and boneThe supporting tissues: connective tissue and its matrix (collagen, elastin), adipose tissue, cartilage, bone and its cells (osteoblasts, osteoclasts, osteocytes), bone remodelling and its diseases (osteoporosis, scurvy, rickets).
- Embryology: from the first days to the three germ layersThe first weeks of development: fertilisation, cleavage, blastocyst and implantation, gastrulation and the three germ layers with what each becomes, neurulation, and what clinical practice draws from it (ectopic pregnancy, spina bifida, teratogens, twins).
- Energy metabolismHow the cell draws energy from glucose and fat: glycolysis, lactic fermentation, the Krebs cycle, the respiratory chain and ATP synthase, beta-oxidation, gluconeogenesis and ketone bodies, with the clinical situations that reveal them.
- Enzymes and their kineticsHow enzymes speed up reactions: active site, activation energy, maximum velocity and Km, competitive and non-competitive inhibitors, cofactors, and the use of enzymes in medicine, as drug targets and as blood markers.
- Inheritance of genetic diseases and chromosomal abnormalitiesThe modes of inheritance (autosomal dominant, autosomal recessive, X-linked) with risk calculation, the karyotype, and the main chromosomal abnormalities (trisomy 21, Turner and Klinefelter syndromes, translocations).
- Replication, transcription and translationFrom DNA to protein: the structure of DNA and RNA, semi-conservative replication, transcription and splicing, translation by the ribosome, and what mutations do (substitution, frameshift, stop codon), with their diseases.
- The 20 amino acidsThe 20 amino acids of proteins: their three-letter and one-letter codes, then the amino acid of each letter, including the least obvious (R, N, D, E, Q, K, F, W, Y). On the back, whether it is essential.
- The cell and its organellesThe compartments of the eukaryotic cell and what they do: nucleus, mitochondria, endoplasmic reticulum, Golgi apparatus, lysosomes, peroxisomes, ribosomes and cytoskeleton, the path of a secreted protein, and the diseases that reveal each organelle.
- The cell cycle, mitosis and meiosisHow a cell divides: the phases of the cycle and its checkpoints, the stages of mitosis, meiosis that makes gametes and shuffles genes, and what happens when division goes wrong (cancer, trisomies).
- The genetic codeThe 64 messenger RNA codons and what they code for, in the standard genetic code: 61 codons for 20 amino acids, 3 stop codons, and AUG, which starts translation. On the back, the synonymous codons.
- The membrane and transportHow molecules get into and out of the cell: the lipid bilayer, simple and facilitated diffusion, osmosis, primary and secondary active transport, endocytosis and exocytosis, and their medical uses (infusions, rehydration, drugs).
- Tissues and epitheliaThe four basic tissues, then the epithelia in detail: lining or glandular, simple or stratified, squamous, columnar or pseudostratified, their basement membrane and junctions, and what pathology draws from them (metaplasia, carcinoma).
- VitaminsThe 13 vitamins, fat-soluble (A, D, E, K) and water-soluble (the B group and C): what each does, its sources and what its deficiency causes (scurvy, rickets, beriberi, pellagra, anaemias), with the situations where supplementation is a must.
Mathematics
- Adjacency matrix and adjacency listsStoring a graph in a machine: adjacency matrix, adjacency lists, edge list, incidence matrix, memory cost and cost of operations, powers of the matrix.
- Algebraic identities and factoringExpanding and factoring: distributivity, the three algebraic identities, common factors and the completed-square form of a quadratic.
- Arithmetic and geometric sequencesThe two reference sequences: definition by recurrence, common difference or ratio, general term, monotonicity and sum of the first terms, then spotting them in a situation (simple or compound interest, doubling, depreciation).
- Assignment problemAssigning n agents to n tasks at the lowest cost: cost matrix, bipartite model, the Hungarian method (row then column reduction, covering the zeros, adjustment) and reading off the optimal assignment.
- Bellman-Ford algorithmShortest paths from a source with arbitrary weights: passes that relax every arc, the table pass after pass, early stop, detecting a negative-weight cycle, the cost and the link with distance-vector routing.
- Binary tree traversalsThe four traversals of a binary tree (preorder, inorder, postorder, level order), their visit order, the link with prefix, infix and postfix notation of an expression, and rebuilding the tree from two traversals.
- Breadth-first searchBreadth-first search of a graph from a source: queue, marking, visit order, search tree, distances in number of edges, unweighted shortest path and O(n + m) cost.
- Canonical forms of a Boolean functionBoolean function of 2 to 4 variables and its normalised written forms: minterms and maxterms, first and second canonical forms, Σm and ΠM notations, from the table to the form and back.
- Cardinality of a setCardinality of a finite set, the sum and product rules, inclusion-exclusion for two and three sets, the cardinality of a complement and the pigeonhole principle.
- Cartesian product and power setPairs and n-tuples, the Cartesian product A × B and Aⁿ, the power set P(E), partitions of a set, with their cardinalities and the encoding of a subset as a bit vector.
- Choosing a statistical chartThe chart that suits each type of variable: bars, sticks, histogram, cumulative frequency polygon, box plot, scatter plot.
- Classification with logistic regressionSorting into two groups with a mathematical model: linear score, sigmoid function, probability, decision threshold, straight boundary, reading a coefficient as an odds ratio, and the clouds a line cannot separate.
- Composition of functionsThe composite g ∘ f: when it exists, reading order, non-commutativity, associativity, the identity, the inverse of a composite, and composites of injections or surjections.
- Conditional probability and independenceProbability of A given B, reading it in a two-way table and in a weighted tree, the product rule, the independence test, and the difference between mutually exclusive and independent events.
- CongruencesComputing modulo n: compatibility with sums, products and powers, modular inverse, divisibility rules, casting out nines and the Luhn check digit.
- Connected components and topological sortTwo applications of traversals: labelling the connected components of an undirected graph, and ordering the vertices of a directed acyclic graph (Kahn by in-degrees, or reverse finish order of a depth-first search); a circuit makes the sort impossible.
- Connectives and truth tablesPropositions, truth values and connectives (not, and, or, exclusive or, implication, equivalence): reading a table, translating a sentence into a formula and spotting tautologies and contradictions.
- Continuous distributionsThe density and the cumulative distribution function, probability seen as an area, then the continuous uniform, exponential (with its memorylessness) and normal distributions.
- Convergence of a sequenceFinite or infinite limit of a sequence, reference sequences, comparison and squeeze theorems, bounded monotone sequences, behaviour of a geometric sequence according to its ratio, and finding a threshold.
- Correlation and regressionThe coefficient r, explained variance, the regression line and the difference between correlation and causation.
- Depth-first searchDepth-first search of a graph: recursive and stack versions, discovery and finish order, search tree, backtracking, cycle detection and O(n + m) cost.
- DerivativesDerivative at a point and tangent line, derivatives of standard functions, calculation rules (sum, product, quotient, composition), sign of the derivative and variations, extrema and the equation of the tangent.
- Descriptive statisticsMean, median, standard deviation, quartiles and the normal distribution, applied to fitness test results.
- Determinant and inverse of a matrixComputing a determinant (2 × 2, Sarrus, expansion along a row, triangular), deciding whether a matrix is invertible, computing its inverse and solving AX = B with it.
- Diagnostic testsJudging a test: sensitivity and specificity, positive and negative predictive values and how they depend on prevalence, false positives and false negatives, choosing the threshold and the ROC curve, likelihood ratios, with calculations on real cases.
- Digital tools for statisticsDoing the path's calculations in a spreadsheet and in Python: spreadsheet functions, pivot table, numpy, pandas, matplotlib, and the n versus n − 1 divisor trap.
- Dijkstra's algorithmShortest paths from a source in a graph with positive weights: the table of tentative distances and predecessors, picking the closest vertex, updating its neighbours, reading the path back, the failure with a negative weight and the cost with a priority queue.
- Discrete distributionsThe discrete uniform, Bernoulli, binomial, geometric and Poisson distributions: the situation each one models, its parameters, its formula, its expected value and variance, and the approximation of a binomial by a Poisson distribution.
- Equations and inequalitiesFirst-degree equations and inequalities, zero product, quadratics with the discriminant, quotients and sign tables, and writing the solution set as intervals.
- Equivalence relationsA reflexive, symmetric and transitive relation: equivalence classes, representatives, the quotient set and the associated partition, with congruence modulo n, same square or same number of 1 bits.
- EstimatorsFrom the unknown parameter to its point estimate: parameter and statistic, estimating a mean, a proportion and a variance (dividing by n − 1), bias, variance, convergence and mean squared error.
- Euclidean divisionThe theorem a = bq + r with 0 ≤ r < b, for a positive or negative dividend, divisibility, and the gap between the mathematical remainder and the % operator of programming languages.
- Eulerian and Hamiltonian graphsWalking every edge once (Eulerian trails and circuits, Euler's theorem, the Königsberg bridges, the Chinese postman) or every vertex once (Hamiltonian paths and cycles, the travelling salesman): two neighbouring questions, two very different difficulties.
- Expected value and variance of a random variableThe discrete random variable and the table of its distribution, expected value, variance and standard deviation, linearity of expectation, the effect of an affine change on the variance, sums of independent variables and the fair game.
- Floyd-Warshall algorithmShortest paths between every pair of vertices: the distance matrix, step k, the update formula, loop order, the successor matrix, the O(n³) cost and choosing the right shortest-path algorithm.
- Fractions, powers, rootsThe calculation rules for fractions, powers (zero and negative exponents, powers of 2 and 10, scientific notation) and square roots: knowing which are valid and which are classic mistakes.
- Gantt chartThe Gantt chart as a calendar view of a schedule: bars, dependencies, earliest or latest placement, visible float, critical path, milestones, progress and load per resource.
- Gaussian eliminationSolving a linear system by Gaussian elimination: augmented matrix, row operations, row echelon form, back-substitution, and the three possible outcomes (one solution, none, infinitely many).
- GCD, Euclid's algorithm and BézoutGCD and LCM, Euclid's algorithm, coprime integers, Bézout's identity, Euclid's lemma (Gauss's theorem in France) and the integer equations ax + by = c.
- Gradient descentMinimising a function by following the slope: derivative and gradient, update rule, choice of step, convergence, oscillation and divergence, local minimum and stopping criterion.
- Graph colouringColouring the vertices of a graph so that two neighbours differ: chromatic number, bounds from cliques and the maximum degree, greedy colouring and vertex order, bipartite graphs, and timetabling problems seen as colourings.
- Heuristics and metaheuristicsLooking for a good solution when the best is out of reach: greedy, local search and local optimum, then simulated annealing, tabu search and the genetic algorithm, and the trade-off between quality and computing time.
- Implication, contrapositive, converseImplication and its variants: table, necessary and sufficient conditions, converse, contrapositive, negation, and the two classic invalid arguments.
- Induction and recursionProof by induction (base case, inductive step, conclusion; simple and strong induction) and its programming twin: base case and recursive call, termination and correctness of a recursive function.
- Injection, surjection, bijectionFunctions from one set to another: image, preimage, injective, surjective and bijective functions, the inverse function, and what the cardinalities of finite sets allow.
- Karnaugh mapsThe Karnaugh map with 2, 3 and 4 variables: Gray order, plotting a function, groups of 1, 2, 4 or 8 adjacent cells, the term of each group, the minimal expression and don't-care cases.
- Kruskal's and Prim's algorithmsThe minimum spanning tree of a weighted graph: Kruskal's algorithm (edges by increasing weight, refusing those that close a cycle), Prim's (growth from one vertex), the greedy justification and uniqueness.
- Lagrange interpolationThe polynomial of degree at most n through n + 1 points: existence, uniqueness, basis polynomials, computing small examples, interpolation error and Runge's phenomenon.
- Least squares methodFitting a model to measurements by minimising the sum of squared vertical gaps: residuals, the least-squares line, normal equations, parabola fits and linearising an exponential or power model.
- LikelihoodThe likelihood function of a sample, the log-likelihood and the maximum likelihood method on four distributions (Bernoulli, Poisson, exponential, normal): write, take the logarithm, differentiate, set to zero.
- Limits and comparative growthLimits at infinity and at a point, operations on limits, the four indeterminate forms, horizontal and vertical asymptotes, and the comparative growth of logarithms, powers and exponentials.
- Logical equivalences and De Morgan's lawsThe usual equivalences of propositional calculus, De Morgan's laws, negating a formula and rewriting a program condition without negation.
- Markov chainsSystems that move from one state to another at random: probability graph, transition matrix, distribution after several steps, absorbing states, stationary distribution and the idea behind PageRank.
- Matching in a graphMatching in a bipartite graph: maximal and maximum matchings, free vertex, alternating and augmenting paths, the augmenting-path algorithm and Hall's condition.
- Matrix multiplicationMultiplying two matrices: the condition on dimensions, the row-by-column calculation, non-commutativity, the identity matrix, powers and the product of a matrix by a column vector.
- Matrix operationsThe vocabulary of matrices (dimensions, entries, special matrices) and the entry-by-entry operations: sum, multiplication by a real number and transpose.
- Maximum flowFlow networks, feasible flows, residual graph and augmenting paths, the Ford-Fulkerson algorithm, cuts and the max-flow min-cut theorem.
- Methods of proofThe six ways of proving: direct, by contrapositive, by contradiction, by cases, by counterexample and by induction, with the structure of each.
- Minimax and alpha-betaChoosing a move in a two-player zero-sum game: game tree, evaluation function, limited depth, minimax back-up, alpha-beta pruning and the effect of move ordering.
- Modelling a linear programmeGoing from a word problem to a linear programme: decision variables, objective function, constraints, sign conditions, feasible solution, and what makes a relation linear or not. Three typical problems: production, blending, transport.
- Multiple linear regressionPredicting a quantity with a linear model on several variables: reading a coefficient, residuals, R² and adjusted R², the residual plot, polynomial terms, overfitting and the limits of extrapolation.
- Numeration in base bWriting an integer in any base: successive divisions, Horner's scheme, number of digits, the largest integer with n digits and column addition.
- Numerical integrationApproximating a definite integral with rectangles, trapezoids and Simpson's rule: composite formulas, the sign of the error according to monotonicity and convexity, and the order of each method.
- Order relationsA reflexive, antisymmetric and transitive relation: total or partial order, Hasse diagram, maximal elements and maximum, upper bounds, least upper bound, and the usual orders (≤, divisibility, inclusion, lexicographic).
- Paths, cycles, connectivityWalks and paths, cycles and circuits, distance and diameter, connectivity of a graph, bridges, reachability and strong connectivity in a directed graph.
- Permutations, arrangements, combinationsCounting choices: lists with repetition, arrangements, permutations, anagrams, combinations, binomial coefficients, Pascal's triangle and the binomial theorem.
- PERT and MPMScheduling a project from its task table: levels, earliest and latest dates, total and free float, critical tasks, minimum project duration, MPM and PERT graphs with dummy tasks.
- Polynomial long divisionDividing a polynomial A by a non-zero polynomial B: A = BQ + R with a remainder of degree strictly less than that of B. The remainder of division by (x − a), divisibility and Horner's scheme.
- Polynomials: degree, roots, factoringPolynomials with real coefficients: degree, sum and product, root and multiplicity, factoring by (x − a), maximum number of roots, complete factoring of a degree 2 or 3 polynomial with an obvious root.
- Prime numbersDefinition, the sieve of Eratosthenes, trial division up to the square root, prime factorisation, number of divisors and the infinitude of primes.
- Properties of a binary relationA binary relation on a finite set, given by its pairs, its matrix or its graph: reflexivity, symmetry, antisymmetry, transitivity, the converse relation and the transitive closure.
- Properties of Boolean algebraBoolean algebra on {0, 1}: sum, product, complement, its laws (distributivity, neutral and absorbing elements, idempotence, complementation, absorption, De Morgan, duality) and algebraic simplification.
- Putting the normal distribution to workStandardising, reading the normal table in both directions, intervals at one, two and three standard deviations, the usual quantiles and the approximation of a binomial by a normal distribution.
- QuantifiersPredicates, the quantifiers ∀, ∃ and ∃!, free and bound variables, quantifier order and negating a quantified statement.
- QueueingKendall notation, then the M/M/1 queue end to end: utilisation, stability, mean number of customers, time in system and waiting time, Little's law, and a service that clogs up.
- Random number generatorsHow a computer manufactures chance: seed, linear congruential generator and period, simulating a distribution from a uniform number, and why simulation and security do not use the same generator.
- Reading a research paperThe IMRAD structure, the abstract, peer review and levels of evidence.
- Reading the graph of a functionReading a curve: image, preimage, extremum, direction of variation, slope between two points, graphical solving of f(x) = k and f(x) ≥ k, then going from the curve to the table of variations.
- Recursively defined sequencesSequences in which each term is computed from the previous one by a function f: first terms, cobweb plot, fixed point, arithmetico-geometric sequences reduced to a geometric one, and order-2 recurrences such as Fibonacci.
- Roman numeralsRead and write Roman numerals: from 1 to 20, the tens and hundreds, then famous years (MDCCLXXXIX, MCMXLV…). On the back, each number broken down symbol by symbol.
- Rounding errorsWhat floating-point computation does to results: absolute and relative error, machine epsilon, absorption, catastrophic cancellation, accumulation, comparing with a tolerance, and the difference from method error.
- Sample spaces and eventsDescribing a random experiment by its sample space and its events, combining events (union, intersection, complement, mutual exclusivity), computing a probability by equiprobability and with the complement and union formulas.
- Set operationsMembership and inclusion, the empty set, defining a set by listing or by a property, union, intersection, difference, symmetric difference, complement, Venn diagrams and De Morgan's laws.
- Solving a linear programme on a graphSolving a two-variable programme on the plane: line and half-plane of each constraint, feasible region, isoprofit lines, optimal vertex, the vertex method and the four possible outcomes.
- Solving f(x) = 0: bisection, Newton, fixed pointThe three iterative root-finding methods: bisection, Newton's method and fixed-point iteration, with when each one works, when it fails, how fast it converges and when to stop.
- Special graphsThe families of graphs to know: complete, chain, cycle, star, tree, bipartite, regular, planar, weighted, directed acyclic, complement and subgraph.
- Standard functionsThe reference functions: affine, square, cube, inverse, square root, absolute value, exponential, logarithms, sine and cosine. Domain, shape, variations, special values, algebraic properties and the effect of a shift on the curve.
- Statistical analysis librariesDoing the path's calculations in Python: scipy.stats (quantiles, t.interval, t-tests, chi-squared), statsmodels for a proportion's interval, pandas for the contingency table; the R equivalents are named.
- Statistical distributions and testsThe statistical tools of the programme: mean, median and standard deviation, the normal distribution, confidence intervals, the null hypothesis and the p-value, alpha and beta risks and power, Student's t and chi-squared tests, correlation, and the interpretation traps.
- Student's t-testStudent's distribution and its degrees of freedom, then the three tests on means: one sample against a value, two independent samples, two paired series; statistic, reading the table and conditions of use.
- Study designs and levels of evidenceReading a study: randomised trials, cohorts, case-control and cross-sectional studies and meta-analyses, relative risk, odds ratio and number needed to treat, biases and confounders, and the grading of HAS recommendations.
- The A* algorithmShortest-path search guided by an estimate: cost paid, estimate of the rest, open and closed lists, admissible and consistent heuristics, and what A* becomes with a zero heuristic (Dijkstra) or with the heuristic alone (greedy search).
- The central limit theoremWhy sums and averages take a bell shape, how much a sample mean tightens as the sample grows, when you can rely on it and how to work out a probability on a sum.
- The chi-squared testThe two uses of the chi-squared test: fit to a stated distribution and independence of two characteristics in a contingency table; expected counts, statistic, degrees of freedom, reading the table and the condition of counts of at least 5.
- The confidence intervalThe confidence interval of a mean and of a proportion: standard error, quantile, margin of error, bounds, what the confidence level means and the sample size that guarantees a given margin.
- The decision treeDeciding when the future is uncertain: decision and chance nodes, expected value, rolling the tree back, the value of perfect information, then the maximin, maximax, Laplace and minimax-regret criteria when there are no probabilities.
- The knapsack problemThe 0/1 knapsack and its fractional version: the greedy rule by value-to-weight ratio and its limits, dynamic programming on the capacity, the fractional bound and branch and bound.
- The law of large numbersWhy an observed frequency approaches the probability, what the Chebyshev inequality guarantees, how many draws give what precision, why chance never catches up and how the Monte Carlo method takes advantage.
- The linear programme: standard form and dualityThe linear programme with several variables: putting it in standard form with slack variables, the dual programme and the price of a resource, integer variables and relaxation, and using a solver.
- The Poisson processRandom arrivals at a constant rate: number of arrivals over a period, time between two arrivals, memorylessness, merging and splitting streams, and the cases where the model fails.
- The scientific methodHypothesis, variables, control group, randomisation and bias: building a protocol that proves something.
- The simplex algorithmThe simplex method with tableaux for a maximisation problem: choosing the entering variable and the pivot, one iteration, the stopping rule, reading the solution and the path from vertex to vertex.
- The spread of a seriesRange, interquartile range, variance, standard deviation, coefficient of variation, box plot, outliers, and the effect of a shift or a change of unit.
- The travelling salesman problemThe shortest round trip through every city once: the explosion in the number of tours, construction by the nearest neighbour, improvement by swapping two edges, and the bound given by the minimum spanning tree.
- The vocabulary of statisticsThe words of a statistical study: population, sample, individual, variable, category, variable types, counts, relative frequencies and cumulative values.
- Times tablesThe 2 to 10 times tables, one table at a time: the 90 products to know by heart, from 2 × 1 to 10 × 10. On the back, the trick of each table.
- Total probability and Bayes' formulaPartition of the sample space, the total probability formula, Bayes' formula with its prior, likelihood and posterior probabilities, and the base rate fallacy with a test or filter that is rarely wrong.
- Transitive closureThe transitive closure of a directed graph: reachability, reachability matrix, Warshall's algorithm and its cost, computing it by traversals and strongly connected components read off the matrix.
- Trees and spanning treesThe tree as a connected graph without cycles, its characterisations (n − 1 edges, a single path between two vertices), forests, leaves, rooted trees and the spanning tree of a connected graph.
- Vectors, lines, dot productIn an orthonormal frame of the plane: vector coordinates, collinearity, norm and distance, equations of a line, direction and normal vectors, parallelism, intersection, dot product, orthogonality and angle.
- Vertices, edges, degreesThe basic vocabulary of graphs, directed or not: vertex, edge, arc, loop, simple graph, order, size, degree, the handshaking lemma and degree sequences.
Physical sciences
- Atomic numbersThe atomic number Z of the first 36 elements, from hydrogen to krypton, period by period.
- Chemical familiesThe family of each element of the periodic table: alkali, alkaline earth and transition metals, post-transition metals, metalloids, nonmetals, halogens, noble gases, lanthanides and actinides. The elements whose properties are only predicted (darmstadtium to oganesson) are left out.
- Chemical symbolsThe symbol of the 118 elements of the periodic table, period by period. For each element, pick its symbol among four that look alike. On the back, the origin of the symbols that do not come from the element's name (Na, K, Au, Hg…).
- Electron configurationThe electron configuration of the first 36 elements, from the element to its configuration and back. The exceptions to the Madelung rule (chromium, copper) are explained on the back.
- ElectronegativityWhich of two neighbouring elements is more electronegative? The s- and p-block elements up to xenon, compared across a period and down a group, with their Pauling values on the back.
- Osmosis, pressures and flowThe physical laws of body fluids: osmotic and oncotic pressure, the tonicity of infusions, the Starling balance in capillaries and how oedema forms, diffusion, and blood flow (flow, resistance, Poiseuille's and Laplace's laws).
- Radioactivity and radiation protectionIonising radiation in medicine: the kinds of radiation and what stops them, half-life, the becquerel, the gray and the sievert, irradiation and contamination, and the rules of radiation protection (time, distance, shielding) applied to imaging and nuclear medicine.
- Symbols → elementsFrom the symbol to the element, for the 118 elements of the periodic table, period by period: Fe is iron. On the back, the Latin origin of the surprising symbols.
- The International System of UnitsThe 7 SI base units, its 19 most common derived units (newton, pascal, joule, watt, volt, ohm…) and 15 prefixes, from femto to exa. For each unit, the quantity it measures and the reverse; on the back, its definition in base units.
- The optics of the eyeThe eye as an optical instrument: the cornea and lens, accommodation, the dioptre, vision defects (myopia, hyperopia, presbyopia, astigmatism) and their correction, the retina with its cones and rods.
- Understanding the periodic tableRead the table instead of learning it by heart: deduce from an element's place its valence electrons, its number of shells, the ion it forms, whether it is a metal, its block, and compare radii and electronegativities. Every answer explains why.
Sport
- Acrosport: pyramids, roles and safetyBase, top and spotter, safe support points, holding figures, mounting and dismounting, and composing a routine.
- Adolescence and sportGrowth spurt, temporary clumsiness, biological age and dropout: what puberty changes in sport.
- Angular kinematicsAngles, angular velocity and the link between rotation and linear speed at the end of a limb.
- Anxiety and performanceThe inverted U, cognitive and somatic anxiety, the catastrophe model and individual zones of optimal functioning.
- Artistic gymnastics: apparatus and the code of pointsThe six men's and four women's apparatus, the D and E scores, deductions and apparatus sizes.
- Assessment in PEDiagnostic, formative, assessment as learning, summative; success and process criteria; self and peer assessment.
- Athletics: running, jumping and throwingThe track, the lanes, the false start, the relay, the attempts in jumps and throws, and the phases of a long jump.
- Badminton: the net, the serve and scoringThe court, net height, the serve below 1.15 m, the service court by score and games to 21 (to 15 from 4 January 2027).
- Basketball: the court, the clocks and foulsThe FIBA court, the 3.05 m basket, the three-point line, 24 seconds, 8 seconds and fouls.
- Boxing: legal blows, rounds and decisionsTarget areas, banned blows, rounds, the count, judges and educational boxing at school.
- Centre of mass and stabilityCentre of mass, base of support and balance, from judo to the Fosbury flop.
- Children's motor developmentFrom primitive reflexes to the golden age of learning: the major milestones, their ages and the laws that order them.
- Climbing: belaying, knots and disciplinesThe belay chain, the figure-of-eight, the partner check, knots and their uses, and the three Olympic disciplines.
- Coach leadershipChelladurai's multidimensional model, autocratic and democratic styles, and coaching behaviours.
- Cohesion and group dynamicsTask and social cohesion, the Ringelmann effect and social loafing: what makes a team more, or less, than the sum of its players.
- Confidence and self-efficacyBandura's self-efficacy and its four sources, from strongest to weakest.
- Coubertin and OlympismPierre de Coubertin, the Sorbonne congress, the IOC and the first modern Games: the ideas, symbols and dates of Olympism.
- Dance: composing a choreographyMovement parameters, compositional devices, the roles of choreographer, performer and spectator, and the creative process.
- Doping and healthThe classes of the prohibited list, the effect each is used for and what it does to the body.
- Endurance trainingMaximal aerobic speed, intensity zones, continuous, intermittent and interval training, and calculating paces and split times.
- FeedbackKnowledge of results and of performance, intrinsic and extrinsic feedback, and why too much feedback harms learning.
- Field testsShuttle run, VAMEVAL, Cooper, CMJ and Ruffier-Dickson tests: what they measure and how to calculate results.
- Fifteen-a-side rugby: points, knock-ons and tacklesThe points for a try, conversion and penalty, the forward pass, the knock-on, the tackle, the scrum and the lineout.
- First aid (PSC1)Protect, alert, help: cardiac arrest, bleeding, choking and unconsciousness, with the PSC1 actions and numbers.
- Flexibility and stretchingStatic, dynamic, ballistic and PNF stretching, and when to place them around exercise.
- Fluid mechanicsDrag, lift and buoyancy: how air and water slow down or hold up the athlete.
- Football: the pitch and the Laws of the GameThe goal, the penalty area, offside, handball, free kicks and cards.
- Forces in sportWeight, ground reaction, friction, drag and buoyancy: the forces acting on an athlete.
- From traditional games to modern sportsSoule and real tennis, the English public schools, codification and the first federations: how games became sports in the nineteenth century.
- Handball: the court, the area and sanctionsThe 40 × 20 m court, the 6 m goal area, the 7 m throw, steps, three seconds and the 2-minute suspension.
- How sport is organised in FranceThe State, the National Sport Agency, the sports movement and local authorities: who does what in French sport.
- Impulse and momentumImpulse, momentum, cushioning landings and how long forces are applied.
- Judo: techniques, scores and penaltiesTori and uke, breakfalls, throws and groundwork, ippon, shido and the phases of a throw.
- Linear kinematicsPosition, average and instantaneous velocity, acceleration: describing straight-line motion.
- Moment of inertia and angular momentumWhy one tucks to spin fast: moment of inertia and conservation of angular momentum.
- Mosston's teaching stylesMosston and Ashworth's spectrum: eleven styles, from command to self-teaching, according to who makes the decisions.
- MotivationIntrinsic and extrinsic motivation, the self-determination continuum, basic needs and achievement goals.
- Newton's lawsInertia, Newton's second law and action–reaction, applied to sport movements.
- Orienteering: the map and the routeMap colours, the control, the scale, setting the map, handrails and route choice.
- PeriodisationMicrocycle, mesocycle and macrocycle, preparation and competition periods, and tapering.
- Physical activity and healthWHO guidelines, METs and intensity, sedentary behaviour and inactivity, and prescribed adapted physical activity.
- Physical qualitiesEndurance, strength, speed, flexibility and coordination: what each means and how it is measured.
- Piaget, Wallon and Vygotsky applied to movementPiaget's stages, Wallon's tonic dialogue and Vygotsky's zone of proximal development: what developmental psychology says about movement.
- Practice conditionsBlocked, random, variable, massed or distributed practice, and mental practice: organising training to retain.
- Preventing injuriesGradual load, the acute-to-chronic ratio, structured warm-ups, eccentric strengthening, sleep and equipment.
- Projectile motionRelease angle, speed and height: what makes a throw or jump go far.
- Quantities and unitsInternational System units, scalars and vectors, and conversions useful in sport.
- Reaction time, Hick's law and Fitts's lawMeasure on yourself the cost of choice and precision: simple and choice reaction time, Hick's law, Fitts's law and anticipation.
- Running a PE lessonMotor engagement time, instructions, set-ups, groups and lesson structure: getting every pupil active.
- Safety in PEActive and passive safety, spotting and assisting, the duty of care and vigilance: teaching without exposing.
- School and university sportUSEP, UNSS and FF Sport U: sport at primary school, secondary school and university.
- Self-organised practices and board sportsSkateboarding, surfing, street workout, running: practices outside federations, their values and their institutionalisation.
- Socialisation through sportPrimary and secondary socialisation, family, club, peers and school: how one becomes a sportsperson and what sport passes on.
- Speed trainingReaction, acceleration, top speed and speed endurance: the parts of a sprint and how to train them.
- Sport and gender"Male" and "female" sports, stereotypes, gendered socialisation and transgression: how sport makes and unmakes gender.
- Sport and politicsPropaganda, boycotts, the Cold War, apartheid and ping-pong diplomacy: how States use sport and how sport responds.
- Sport and womenExclusion, pioneers and conquests: Alice Milliat, the Women's World Games, the first female Olympians and the parity of Paris 2024.
- Sport as spectacle and the mediaBroadcasting rights, sponsorship, sport as spectacle and commodification: how the media transformed sport.
- Sport institutions and their datesWhen the CNOSF, INSEP, UNSS, AFLD and the National Sport Agency were born: the dates that built French sport.
- Sports federationsApproved, delegated, single-sport, multisport and affinity federations: what each one may do.
- Sports injuriesSprain, dislocation, fracture, muscle injuries, tendinopathy and concussion: recognising the injury and responding.
- Sports jobs and qualificationsWho may coach for pay: the professional card, BPJEPS, DEJEPS, the STAPS degree and volunteering.
- Strength training1RM, load percentages, rep ranges, methods and estimating the 1RM.
- Supercompensation and recoveryFatigue, recovery, supercompensation and the Banister model: why the next session must come at the right time.
- Swimming: the four strokes and their rulesFront crawl, backstroke, breaststroke and butterfly, turns and finishes, the 15 m limit and the medley order.
- Table tennis: the table, the serve and gamesThe table and net, the serve tossed 16 cm, the let, games to 11 and alternating serves.
- Teaching approachesBehaviourism, constructivism, social constructivism, part and whole methods, differentiation: how we make pupils learn.
- Teaching PE: didacticsDidactic transposition, the teaching triangle, task variables, problem situations and task types.
- Tennis: the court, scoring and the serveThe court, the net, 15-30-40 scoring, advantage, the set, the tie-break, the let and the double fault.
- The 1901-law associationCreating and running a club: statutes, declaration, general meeting, board and responsibilities.
- The authors of the sociology of sportElias, Dunning, Bourdieu, Pociello, Brohm, Ehrenberg, Bromberger: who said what, and with which concept.
- The civilising process and sportElias and Dunning: self-restraint, the monopoly of violence, the quest for excitement and the sportisation of games.
- The economics of sportWho pays for sport in France: households, local authorities, the State, businesses, TV rights and ticketing.
- The fight against dopingWADA, AFLD, the prohibited list, TUEs and how a test unfolds: how the fight against doping works.
- The French PE curriculumThe common core, the fields of learning in lower and upper secondary school, and timetables: what PE must teach.
- The games of AntiquityOlympia and the Panhellenic games, the events, the sacred truce and the Roman games: what ancient sport was and why it is not the direct ancestor of modern sport.
- The great Olympic GamesFrom Athens 1896 to Paris 2024: the Games that marked history, their political context and their feats.
- The gymnastics methodsAmoros, Ling, Jahn, Demenÿ, Hébert: the great methods of the nineteenth and early twentieth centuries, their aims and their legacy for physical education.
- The history of physical education at schoolFrom compulsory gymnastics in 1880 to the fields of learning: the key stages of physical education in French schools.
- The laws of sportThe 1901 law, the Mazeaud law, the Avice law, the Buffet law, the Sport Code and the 2022 law: what each text changed.
- The Olympic movementThe IOC, national Olympic committees, international federations and organising committees: the architecture of the Olympic movement.
- The principles of trainingOverload, progression, specificity, individualisation, alternation and reversibility: the rules that drive progress.
- The space of sports and distinctionHabitus, capital, distinction and the space of sports: why each social milieu has its sports.
- The sporting practices of the FrenchWho does sport, which one, where and how: licences, unorganised practice, gaps by age, sex and social background.
- The stages of motor learningFitts and Posner's stages and Bernstein's degrees of freedom: how a movement goes from discovery to automaticity.
- The warm-upEffects, structure from general to specific and the RAMP method.
- Theories of motor learningAdams's closed loop, Schmidt's schema, the motor programme, dynamic and ecological approaches: how motor control is explained.
- Torques and leversTorque, moment arm and the three classes of levers in the human body.
- Training loadVolume, intensity, density, external and internal load, and the session-RPE method to measure it simply.
- Transfer of learningPositive, negative, near, far and bilateral transfer: when what was learned helps, or hinders, another task.
- Violence and fandomSupporters, ultras and hooligans, violence in and around stadiums, and how institutions respond.
- Volleyball: the net, contacts and rotationThe 18 × 9 m court, net heights, three contacts, the block, rotation, the libero and set scoring.
- Work, energy and powerWork of a force, kinetic and potential energy, mechanical power and their calculation.
- Wrestling: styles, the fall and pointsFreestyle and Greco-Roman, the fall, the takedown, technical superiority, bout length and passivity.