Lexicon

Every term the course teaches, 433 in all, with its French equivalent, what it means and the lesson parts where you meet it.

#

!important!important: a marker that makes a style rule beat the usual rules, and makes every later change harder.Look and layout: What to ask
.env filefichier .env: a file on your computer that holds the project's environment variables and must never be committed.Working with an agent: What to ask

A

Above the foldau-dessus de la ligne de flottaison: the part of a page that shows on the screen before anyone scrolls.Layout and space: What you see first
Accent colourcouleur d'accent: a bright colour used in a few places only, to draw the eye.Type and colour: Palette and colour roles
Acceptance criteriacritères d'acceptation: checks anyone can run to decide whether a piece of work is finished.The brief: What this version won't do, and when the work is done
Accessibilityaccessibilité: how well people with a disability can use a site, for example with a screen reader, the keyboard or larger text.Structure and meaning: Checking a page without reading code
Accessibility treearbre d'accessibilité: the page as screen readers receive it, with its headings, links, buttons and text, shown in the Elements panel.Structure and meaning: Checking a page without reading code
Accessibility widgetwidget d'accessibilité: an icon added to a site that promises to make it accessible in one line of code, without changing the HTML.Structure and meaning: Checking a page without reading code Structure and meaning: What to ask
Accordionaccordéon: a list of titles that open and close to show their content, as in a list of questions.Components and states: Things that open on top of the page
Accountcompte: the record a site keeps for one person on its servers, which they reach by logging in from any device.Where data lives: Three places data can live Where data lives: Without an account, the browser remembers
Active or pressedactif, enfoncé: the state of a button at the moment it's clicked or tapped.Components and states: States
addEventListeneraddEventListener: the JavaScript instruction that creates an event listener, as in button.addEventListener("click", …).Behaviour: Waiting for events
Admin screenback-office: the private pages where a team edits a site's content, such as texts and images, without touching code.Front and back: Placing a tool on the map Where data lives: Content in the code, or content as data Where data lives: What to ask
Affordanceaffordance: what an element suggests you can do with it, such as a filled button that looks pressable.Components and states: Components and buttons
Agencyagence: a company with a team that designs and builds sites for clients.The brief: What to ask
Agent sessionsession: one conversation with an agent, which starts with an empty context.Working with an agent: When a step breaks something
AI agentagent d'IA: a program that reads and writes a project's files and runs commands, following your requests in a chat.Behaviour: What to ask The browser's toolbox: A page from the disk or from a web server The brief: What to ask Working with an agent: What the agent knows Front and back: A check in the page is only a suggestion Public and secret: A secret key in the page Where data lives: Content in the code, or content as data
Alignmentalignement: placing elements so that they share the same edges, often the same left edge.Layout and space: Grids, columns and alignment
altalt: the attribute of a picture (the img element) that holds its alt text, left empty for a decorative picture.Structure and meaning: Words for the pictures
Alt texttexte alternatif: a short text that replaces a picture, read aloud by screen readers and shown if the picture doesn't load.Structure and meaning: Words for the pictures Structure and meaning: What to ask
Analyticsmesure d'audience, analytics: an outside service that counts visits and records what visitors do on a site, such as Google Analytics.The request path: What to ask Where data lives: Three places data can live
Animationanimation: any movement on a page, such as a slide that moves or an icon that turns.Components and states: Things that open on top of the page
API keyclé d'API: a code that identifies a site to an outside service; a secret key must stay on a server, never in the page.The browser's toolbox: What needs a server Working with an agent: What to ask Public and secret: Keys that are public on purpose
Aspect ratioformat, ratio: the shape of a picture, written as width to height, such as 16:9 for a wide video.Layout and space: One layout for every screen
Attributeattribut: an extra piece of information written inside a tag, such as the address of a link or the alt text of a picture.Structure and meaning: Words for the pictures
Automated testtest automatisé: a small program that checks that code gives the right results, run again after every change.Behaviour: What to ask When it breaks: Wrong answers with no error message Working with an agent: Ask for proof
Avataravatar: a small picture that stands for a person, often a round photo or their initials.Components and states: Components and buttons

B

Back endback-end: the part of a site that runs on a server, such as accounts, data and rules, which visitors never see.The browser's toolbox: A page from the disk or from a web server Front and back: Three places where a website runs Public and secret: What really protects the data What keeps running: When one piece stops
Backgroundfond, arrière-plan: the colour behind the whole page.Type and colour: Palette and colour roles
Backupsauvegarde: a copy of a site's data kept in a safe place, to recover it after a loss or an error.What keeps running: Before the builders leave What keeps running: What to ask
Badgepastille, badge: a small coloured label or number on another element, such as "New" or a count of messages.Components and states: Things that open on top of the page
Bannerbandeau: a wide strip across a page or a section, with a message for every visitor.Components and states: Things that open on top of the page
Blockbloc: any rectangular part of a page, such as a paragraph, a card or a whole section.Layout and space: Margin, padding and white space
Blocking problemproblème bloquant: a problem that stops visitors, such as text they can't read or a button they can't find.Type and colour: How to say it
Bodycorps de la réponse: the main content of a response, such as the HTML of a page or an image file.The request path: One request, one response
Body texttexte courant: the main text of a page, set in the size made for long reading.Type and colour: Size, weight and the type scale
Borderbordure: the line around a box.Layout and space: Margin, padding and white space
Border radiusarrondi: how rounded the corners of a box are, given in pixels.Layout and space: Margin, padding and white space
Brand colourscouleurs de marque: the colours of an organisation's identity, taken from its logo and its documents.Type and colour: Palette and colour roles
Breadcrumbsfil d'Ariane: a line of links that shows where a page sits in the site, such as "Home › Exhibitions › Monet".Components and states: The parts of a page
Breakpointpoint de rupture: the width at which a layout changes, such as one column instead of three below 480 pixels.Look and layout: One page that fits every screen Layout and space: One layout for every screen
Briefbrief: a short document that says what to build, for whom and within which limits.Structure and meaning: What to ask The brief: Who the site is for, and what they must do
Budgetbudget: the amount of money you can spend on the project.The brief: The limits
Bugbug: a mistake in code that makes a program do the wrong thing.Behaviour: One place for the data When it breaks: Wrong answers with no error message Working with an agent: When a step breaks something
Bug reportrapport de bug: a message about a bug, with what you did, what you expected, what you saw and the exact error message.When it breaks: What to ask
Buildbuild, compilation: the step that turns the project's code into the files a browser can run.Working with an agent: When a step breaks something
Build stepétape de build: a program that turns the developers' code into files that the browser can run.Behaviour: What frameworks are for
Buttonbouton: an element that does something on the page, such as opening a menu or sending a form.Structure and meaning: Links and buttons do different jobs

C

Cachecache: a store of files kept for reuse, for example in your browser, so they don't have to be downloaded again.The request path: Copies of the files, close to you
Call to action or CTAappel à l'action: an element that asks visitors to act, such as "Book a ticket" or "Contact me".Components and states: Components and buttons
Captionlégende: the short text that goes with a photo or a figure and says what it shows.Type and colour: Size, weight and the type scale
Cardcarte: a box that shows one item, such as a project, with a picture, a title and a short text.Layout and space: What belongs together
Carouselcarrousel: a component that shows one slide at a time, with arrows to see the next one.Components and states: Things that open on top of the page
Cascadecascade: the rules that CSS follows to decide which style rule wins when several apply to the same element.Look and layout: What to ask
CDNCDN: a network of servers in many cities that keeps copies of a site's files and sends them from near each visitor.The request path: Copies of the files, close to you The request path: What to ask
Centred layoutmise en page centrée: a layout where each line and block is placed in the middle, good for short pages only.Layout and space: Grids, columns and alignment
Certificatecertificat SSL: a digital file that proves a site really owns its address, which the browser checks before it shows the padlock.The request path: From address to page What keeps running: A website is rented piece by piece What keeps running: When one piece stops
Change requestdemande de modification: a change to the brief, asked for during the work, which may cost time and money.The brief: What to ask
Checkboxcase à cocher: a small square that a visitor ticks, for a yes or no question or for several choices.Components and states: Forms
Classclasse: a name given to elements in the HTML, such as class="buy", so that one style rule can apply to all of them.Look and layout: Naming each colour and size once
Clear browser dataeffacer les données de navigation: to delete the cookies, local storage and cached files that a browser keeps for websites.Where data lives: Without an account, the browser remembers
Clickable prototypeprototype cliquable: a mockup whose buttons and links work, so that you can try a path through the site.Layout and space: What to ask
Client-side checkvalidation côté client: a check that runs in the visitor's browser, which gives a quick answer but can be changed or skipped.Front and back: A check in the page is only a suggestion
Clipboardpresse-papiers: the place where copied text is kept until you paste it, such as a promo code copied with a button.The browser's toolbox: A toolbox in every browser
CMSCMS: the admin screen where people write and publish a site's content without editing its code, such as WordPress.Structure and meaning: What to ask Where data lives: Content in the code, or content as data
Colour blindnessdaltonisme: difficulty telling some colours apart, often red and green, which affects about one man in twelve.Type and colour: Naming a colour, and contrast
Colour rolerôle de couleur: the job that a colour does on a page, such as text colour, link colour or error colour.Type and colour: Palette and colour roles
Columncolonne: one of the vertical strips of a grid; a block can take one column or several.Layout and space: Grids, columns and alignment
Commandcommande: a line of text typed in the terminal that tells the computer to do something, such as npm install.Working with an agent: Inside the project
Commitcommit: a saved version of the project, with a short message that says what changed and why.Working with an agent: Plan first, then work in small steps
Componentcomposant: a reusable piece of a page, such as a button or a card, designed once and used everywhere.Components and states: Components and buttons
Component librarybibliothèque de composants: the set of all the components of a site, each with its variants and states.Components and states: What to ask
Component stateétat: one of the ways a component looks, depending on what's happening, such as hover or disabled.Components and states: States
Confirmationconfirmation: the message that tells visitors an action worked, such as "Your appointment is booked".Components and states: What to ask
Consent bannerbandeau de consentement, bandeau cookies: the box that asks visitors to accept or refuse cookies and trackers when they arrive on a site.The request path: What to ask
Consistencycohérence: the same things look and behave the same way on every page, so visitors learn them once.Layout and space: What belongs together
Consoleconsole: the panel of the developer tools that shows the errors and messages of a page's scripts.When it breaks: Reading the console Working with an agent: Ask for proof
Containerconteneur: an invisible box that holds the content of a page and keeps it to a maximum width.Layout and space: Grids, columns and alignment
Container querycontainer query: a CSS rule, written @container, that applies only when the space for a block is narrower or wider than a given width.Look and layout: One page that fits every screen
Content inventoryinventaire de contenu: a list of every text, photo and video the site needs, with who provides each one.The brief: Write the content first
Contextcontexte: all the text the model can see when it answers, such as your messages and the files it has read.Working with an agent: What the agent knows
Context windowfenêtre de contexte: the largest amount of text that a model can see at once, measured in tokens.Working with an agent: How agents go wrong
Contrast ratiorapport de contraste: a measure of the difference in brightness between text and its background, at least 4.5 to 1 for main text.Look and layout: Naming each colour and size once Look and layout: The visitor's own settings Type and colour: Naming a colour, and contrast
Cookiecookie: a small piece of data a site stores in your browser, which the browser sends back to that site with each request.Where data lives: Three places data can live Where data lives: How the site knows it's you
Croprecadrage: cutting off the edges of a picture so that it fits a box of another shape.Layout and space: One layout for every screen
CSSCSS: the language of style rules that decide how each part of a page looks and where it is placed on the screen.Look and layout: One set of rules for every page Structure and meaning: Three layers make one page Front and back: Three places where a website runs
CSS gridgrille CSS: a CSS layout tool that places blocks in rows and columns, such as three projects side by side.Look and layout: One page that fits every screen
CSS variablevariable CSS: a named value in CSS, written like --brand and used as var(--brand), often to hold a design token.Look and layout: Naming each colour and size once

D

Dark modemode sombre: a second set of colours for a site, with dark backgrounds and light text.Look and layout: Naming each colour and size once The browser's toolbox: A toolbox in every browser Type and colour: How to say it
Data filefichier de données: a separate file, such as a list of quiz questions, that a page's script loads after the page.The browser's toolbox: A page from the disk or from a web server The browser's toolbox: What to ask
Data leakfuite de données: a situation where private data can be read by people who should not have access to it.Public and secret: What really protects the data
Databasebase de données: an organised store of data on a server, such as every message left in a guestbook.The browser's toolbox: Before paying for a server Front and back: From pages to a private area Front and back: What to ask Where data lives: Three places data can live Where data lives: What to ask
DDoS attackattaque DDoS: an attack that sends a huge number of requests to a site to overload it until it stops working.The request path: Copies of the files, close to you
Deadlineéchéance: the date when the work must be finished or the site must be online.The brief: The limits
Decision makerdécideur: the one person who makes the final decisions and answers the builder's questions.The brief: Quotes, prices and who decides
Decorative pictureimage décorative: a picture that adds no information to the page, such as a background of waves, which gets an empty alt text.Structure and meaning: Words for the pictures
Defaultréglage par défaut: the choice a tool makes when nobody asks for anything else.Type and colour: How to say it
Default stateétat par défaut: how a component looks when nobody is using it.Components and states: States
Definition of donedefinition of done: the checks that every piece of work must pass before a team calls it finished.The brief: What this version won't do, and when the work is done
Deliverableslivrables: everything the builder hands over at the end, such as the mockups, the code and the accounts.The brief: What to ask
Densitydensité: how much a page shows on one screen, from airy, with few items, to compact, with many.Layout and space: What belongs together
Dependencydépendance: code written by other people that a project uses, and that must be updated regularly.Behaviour: What frameworks are for Working with an agent: Inside the project
Deploydéployer, mettre en prod: to publish a new version of a site, so that visitors see the changes.What keeps running: Is the site broken for everyone, or only for me?Where data lives: Content in the code, or content as data
Design systemdesign system: the shared tokens and reusable blocks, such as buttons and cards, that a site's designers and developers both use.Look and layout: Naming each colour and size once Look and layout: What to ask Components and states: What to ask
Design tokendesign token: a colour, font or spacing defined once under a name, such as "brand colour", which every style rule uses.Look and layout: Naming each colour and size once Look and layout: What to ask Type and colour: How to say it
Dev serverserveur de développement: a small program that shows the site in your browser and reloads it each time a file changes.Working with an agent: Ask for proof
Developer toolsoutils de développement: the panels built into every browser, opened with F12, that show a page's code, style rules and errors.Behaviour: A page that changes while it's open Behaviour: Where is a change on screen saved?Structure and meaning: Checking a page without reading code When it breaks: Reading the console Front and back: A check in the page is only a suggestion Public and secret: Your copy of the page The request path: One request, one response
Device modemode responsive: the view of the developer tools, opened with Ctrl+Shift+M, that shows a page at any screen size.Look and layout: One page that fits every screen
Diffdiff: a view of a change that shows the removed lines in red and the added lines in green.Working with an agent: Ask for proof
Disableddésactivé: the state of an element that can't be used for now, usually shown faded.Components and states: States
Display typefacepolice de titrage: a typeface drawn for large titles and posters, too decorative for a paragraph.Type and colour: Typefaces and fonts
divdiv: an HTML element that is a box with no meaning, used only to group other parts of the page.Structure and meaning: Links and buttons do different jobs
Dividerséparateur: a thin line between two blocks or two items of a list.Layout and space: Margin, padding and white space
DNSDNS: the internet's directory, which converts a domain name into the IP address of the site's server.The request path: From address to page The request path: Copies of the files, close to you What keeps running: When one piece stops
DOMDOM: the live copy of a page that the browser builds in its memory, a tree of all its parts that scripts can change.Behaviour: A page that changes while it's open Behaviour: Where is a change on screen saved?
Domain namenom de domaine: the readable name of a website, such as leboncoin.fr, which its owner rents by the year.The request path: The parts of a web address What keeps running: A website is rented piece by piece
Domain restrictionrestriction de domaine: a setting that lets a public key work only on the websites you list, such as your own domain.Public and secret: Keys that are public on purpose Public and secret: What to ask
Dropdown or selectliste déroulante: a field that opens a list of choices when you click it.Components and states: Forms

E

Edge casecas limite: a difficult value to test a tool with, such as zero, a decimal, a negative number or an empty field.When it breaks: Wrong answers with no error message
Elementélément: one part of a page in the HTML, such as a heading, a paragraph, a link, a picture or a button.Look and layout: One set of rules for every page Structure and meaning: Links and buttons do different jobs
Empty stateétat vide: what a list or a page shows when there is nothing in it yet, with what to do next.Components and states: What to ask
Environment variablevariable d'environnement: a value, such as a key, that the code reads from the computer it runs on.Working with an agent: What to ask Public and secret: A secret key in the page
Error messagemessage d'erreur: the text the console shows when a script fails, with the type of error, what failed, and the file and line.When it breaks: Reading the console When it breaks: What to ask Working with an agent: When a step breaks something
Error stateétat d'erreur: what a field, a list or a page shows when something has failed, with how to fix it.Components and states: What to ask
Estimateestimation: an approximate price or duration, given early, which can still change.The brief: Quotes, prices and who decides
Eventévénement: something that happens on a page, such as a click, a key pressed, a form sent or the page scrolled.Behaviour: Waiting for events
Event listenerécouteur d'événement: an instruction that tells the browser to run some code each time a given event happens.Behaviour: Waiting for events

F

F-patternlecture en F: the path of the eye on a page full of text: across the first lines, then down the left edge.Layout and space: What you see first
Featurefonctionnalité: something the site does for visitors, such as a contact form or project filters.The brief: What this version won't do, and when the work is done
Feedbackretours: comments on a design, sent to the person or the tool that made it.Type and colour: How to say it
FigmaFigma: the online design tool that most designers use to draw mockups and components.Components and states: What to ask
File treearborescence de fichiers: the project's folders and files, shown one inside the other as in a file explorer.Working with an agent: Inside the project
file://file://: the start of an address that means the browser opened the file straight from your disk, with no web server.The browser's toolbox: A page from the disk or from a web server
FirebaseFirebase: a Google service that rents you a ready-made back end, with a database, logins and file storage.Front and back: Placing a tool on the map Public and secret: Keys that are public on purpose Public and secret: What really protects the data
Firewallpare-feu: a filter that blocks some connections on a network, for example to some sites from inside a company.What keeps running: Is the site broken for everyone, or only for me?
Fixed elementélément fixe: an element that stays in the same place on the screen while the page scrolls, such as a chat button.Layout and space: One layout for every screen
Fixed priceforfait: one price agreed in advance for a fixed scope, where any change is paid in addition.The brief: Quotes, prices and who decides
Focal pointpoint focal: the one place on a page or a screen where the eye goes first.Layout and space: What you see first
Focusfocus: the state of the element that the keyboard has reached, shown by a visible outline.Components and states: States
Focus outlineindicateur de focus: the visible outline that shows which link, button or form field the Tab key has reached.Look and layout: The visitor's own settings Look and layout: What to ask Structure and meaning: Checking a page without reading code Structure and meaning: What to ask
Fontfonte: one member of a typeface, in one weight and one style, such as Garamond Bold Italic.Type and colour: Typefaces and fonts
Font sizecorps, taille de police: the size of the letters, given in pixels or in rem.Type and colour: Size, weight and the type scale
Footerpied de page: the band at the bottom of every page, with contacts, social links and the legal notice.Components and states: The parts of a page
Formformulaire: a group of fields that visitors complete and send, such as a contact form.Components and states: Forms
Form fieldchamp de formulaire: a box on a page where a visitor types or chooses something, such as a name or an amount.When it breaks: Wrong answers with no error message
Fragmentancre: the part of a web address after a #, which points to a place on the page and is never sent to the server.The request path: The parts of a web address
Frameworkframework: ready-made code, such as React, Vue or Svelte, that redraws the screen from the state automatically.Behaviour: What frameworks are for Behaviour: What to ask Working with an agent: Inside the project
Free planoffre gratuite: a free level of an online service, with limits on how much you can use it.What keeps running: A website is rented piece by piece What keeps running: When one piece stops What keeps running: What to ask
Freelancerfreelance, indépendant: a person who works alone for several clients, paid per project or per day.The brief: What to ask
Front endfront-end: the part of a website that runs in the visitor's browser, such as the page, its buttons and its forms.Front and back: Three places where a website runs
Full-bleedpleine largeur, à fond perdu: describes a photo or a band of colour that fills the whole width of the screen.Layout and space: Grids, columns and alignment
Functionfonction: a named block of code that does one job and can run again whenever it's needed, such as render.Behaviour: One place for the data
Functional requirementexigence fonctionnelle: something the site must let visitors do, such as sending a message.The brief: Who the site is for, and what they must do

G

GDPRRGPD: the European law on personal data, which applies as soon as a site collects a name or an email.When it breaks: What to ask The brief: The limits Front and back: From pages to a private area Public and secret: What to ask Where data lives: What to ask
Grace perioddélai de grâce: the short time after a domain name expires, when the owner can still renew it before anyone else can buy it.What keeps running: When one piece stops
Gradientdégradé: a smooth change from one colour to another across a surface.Type and colour: Naming a colour, and contrast
Gridgrille: a set of invisible columns that every block of a page is placed on.Layout and space: Grids, columns and alignment
Groupingregroupement: showing that several things belong together, with space, a shared background or a border.Layout and space: What belongs together
Guttergouttière: the empty space between two columns of a grid.Layout and space: Grids, columns and alignment

H

Hallucinationhallucination: a false fact that an AI states with confidence, such as the name of a package that doesn't exist.Working with an agent: How agents go wrong
Hamburger menumenu burger: a button with three lines that opens the menu, used on small screens.Components and states: The parts of a page
Handoffpassation: the moment the designs go to the developers or a coding agent, with everything they need to build.Components and states: What to ask
Handoverpassation: the moment when the builders give the site, its accounts and its documents to the client.What keeps running: Before the builders leave What keeps running: What to ask
Hard-codedcodé en dur: written directly into the code, so it changes only when someone edits the code and publishes again.Where data lives: Content in the code, or content as data
Headeren-tête, header: a label in a request or a response that gives details about it, such as the type of file or how long to keep it.The request path: One request, one response
Headingtitre: a title that the HTML marks as the start of a section, so that screen readers can list it and jump to it.Structure and meaning: Who reads the labels
Heading levelsniveaux de titre: the ranks of the headings in HTML, from h1 for the main heading of a page to h2 and h3 for its sections.Structure and meaning: Links and buttons do different jobs
Headlinetitre, gros titre: the large title at the top of a page or an article.Type and colour: Size, weight and the type scale
Herobannière principale, section héro: the large first section of a page, with the main title, a short text and the main button.Components and states: The parts of a page
Hex colour codecode couleur hexadécimal: a colour written as # and six characters, such as #c2410c for orange or #2563eb for blue.Look and layout: Naming each colour and size once
Hidden fieldchamp caché: a form field that the visitor can't see on the page, but which is in the HTML and can be read and changed.Public and secret: Your copy of the page
Hostinghébergement: the service that stores a site's files and sends them to visitors.Behaviour: What to ask Front and back: From pages to a private area Front and back: What to ask What keeps running: A website is rented piece by piece What keeps running: When one piece stops Where data lives: What to ask
Hosting providerhébergeur: the company that rents you the servers where a site is stored, such as OVH or Netlify.What keeps running: Is the site broken for everyone, or only for me?
Hoversurvol: the state of an element while the mouse pointer is over it, which phones don't have.Components and states: States
hrefhref: the attribute of a link (the a element) that holds the address the link goes to, as in href="/cv".Structure and meaning: Links and buttons do different jobs
HTMLHTML: the language that holds a page's content and labels what each part is, such as a heading, a link or a list.Structure and meaning: Three layers make one page When it breaks: Pages that arrive empty Front and back: Three places where a website runs The request path: From address to page
HTTPSHTTPS: the encrypted connection between a browser and a site, shown by the padlock next to the address.The request path: From address to page
Hueteinte: the colour itself, such as red, blue or purple.Type and colour: Naming a colour, and contrast

I

Iconicône: a small picture that stands for an action or an idea, such as a heart or a magnifying glass.Components and states: Components and buttons
Icon buttonbouton icône: a button that shows only an icon, with a hidden text label for screen readers.Components and states: Components and buttons
idid: an attribute that gives one element a unique name, such as id="count", so that a script can find it.Behaviour: Waiting for events
Illustrationillustration: a drawing used to explain or decorate a page, as opposed to a photo.Components and states: Components and buttons
imgimg: the HTML element that places a picture on the page, with the picture's file named in its src attribute.Structure and meaning: Words for the pictures
Injectioninjection: a flaw where text typed by a visitor is treated by the site as code.When it breaks: Text that becomes code
Inline errorerreur en ligne: an error message shown right next to its field, saying what's wrong and how to fix it.Components and states: States
innerHTMLinnerHTML: the JavaScript instruction that inserts text as HTML, so any tags or code in it become part of the page.When it breaks: Text that becomes code
Inspectinspecter: the right-click choice that opens the developer tools on one part of the page, with its live HTML and style rules.Behaviour: A page that changes while it's open Look and layout: One set of rules for every page Public and secret: Your copy of the page Where data lives: Content in the code, or content as data
Instructions filefichier d'instructions: a file in the project, such as AGENTS.md, with rules the agent reads before each task.Working with an agent: What the agent knows
Internal tooloutil interne: an app built only for a company's own staff, such as a dashboard or a booking tool for the team.Public and secret: Your copy of the page
IP addressadresse IP: the numeric address that computers on the internet use to find and reach each other.The request path: The parts of a web address The request path: From address to page Where data lives: Without an account, the browser remembers
Italicitalique: the sloping style of a typeface, used to stress a word or for the title of a work.Type and colour: Size, weight and the type scale

J

JavaScriptJavaScript: the programming language that browsers run to add behaviour to a page, such as a menu that opens.Behaviour: A page that changes while it's open Structure and meaning: Three layers make one page When it breaks: Pages that arrive empty Front and back: Three places where a website runs
Justified texttexte justifié: text stretched so that every line touches both edges, like a newspaper column.Type and colour: Line height, line length and alignment

K

Kerningcrénage: the space between two particular letters, such as A and V, adjusted so that the word looks even.Type and colour: Line height, line length and alignment

L

Labellibellé: the text that says what a field is for, such as "Email", which stays visible next to the field.Components and states: Forms
Latencylatence: the time a request waits before its answer starts to arrive, which is much longer on a weak mobile connection.The request path: When a site is slow in only one place
Launchlancement, mise en ligne: the moment a site first opens to the public, with real users and real data.Where data lives: What to ask
Layoutmise en page: the way the parts of a page are placed on the screen.Layout and space: Grids, columns and alignment
Legal noticementions légales: a page that says who publishes the site and who hosts it, required on most French sites.The brief: The limits
Letter spacing or trackingapproche: the space between all the letters of a word or a line.Type and colour: Line height, line length and alignment
Librarybibliothèque: ready-made code, written by others, that does one job, such as showing a gallery of photos.Working with an agent: Plan first, then work in small steps
LighthouseLighthouse: a free audit in Chrome's developer tools that scores a page's speed and accessibility and lists its problems.Structure and meaning: Checking a page without reading code The request path: When a site is slow in only one place
Lightnessluminosité: how light or dark a colour is, from black to white.Type and colour: Naming a colour, and contrast
Line height or leadinginterlignage: the distance from one line of text to the next, often 1.4 to 1.6 times the size of the letters.Type and colour: Line height, line length and alignment
Line length or measurelongueur de ligne: the number of characters in one line of text, best at about 60 to 75.Type and colour: Line height, line length and alignment
Linklien: an element that goes somewhere, to another page or another place on the same page, with an address you can share.Structure and meaning: Links and buttons do different jobs Components and states: The parts of a page
Lintlint: a check that reads the code and lists common mistakes, without running it.Working with an agent: Ask for proof
Listliste: items shown one under the other, one on each line, which fits more on a screen than cards.Layout and space: What belongs together
Loading stateétat de chargement: what a screen or a list shows while its content arrives.Components and states: What to ask
Local serverserveur local: a web server running on your own computer, reached at an address that starts with http://localhost.The browser's toolbox: A page from the disk or from a web server The browser's toolbox: What to ask
Local storagestockage local: a place in the browser where a page keeps small things, such as a dark mode choice, on this device only.The browser's toolbox: A toolbox in every browser The browser's toolbox: What needs a server Where data lives: Three places data can live Where data lives: Without an account, the browser remembers
Localhostlocalhost: the name a computer gives itself, so an address such as localhost:5173 opens only on that computer.Working with an agent: Ask for proof
localStoragelocalStorage: the JavaScript name for local storage, where setItem saves a value and getItem reads it.The browser's toolbox: A toolbox in every browser
Lock-indépendance au fournisseur: the situation where leaving a tool is hard, because your site and data only work inside it.Front and back: Placing a tool on the map Front and back: What to ask What keeps running: Before the builders leave
Log outse déconnecter: to end your session, so that the browser's session cookie no longer opens your account.Where data lives: How the site knows it's you
Logged outdéconnecté: not signed in to any account, so the site treats you as an unknown visitor.Public and secret: What really protects the data
Loginconnexion: the step where a person proves who they are to a site, usually with an email address and a password.Front and back: From pages to a private area Where data lives: How the site knows it's you
Logologo: the symbol or the name of the organisation, usually in the header, which links to the home page.Components and states: The parts of a page
Logslogs, journaux: the record a server keeps of what it did, with the time of each action and any errors.What keeps running: Is the site broken for everyone, or only for me?
Lorem ipsumlorem ipsum, faux texte: fake Latin text that designers use as placeholder text.The brief: Write the content first

M

Maintenancemaintenance: the regular work that keeps a site working after launch, such as updates, fixes and renewals.Front and back: What to ask Where data lives: Content in the code, or content as data
Marginmarge: the space outside a box, between it and its neighbours or the edge of the screen.Layout and space: Margin, padding and white space
Matter of tastequestion de goût: a personal preference, such as a favourite colour, which doesn't stop any visitor.Type and colour: How to say it
Maximum widthlargeur maximale: the widest that a block or a text may become, even on a very wide screen.Layout and space: Grids, columns and alignment
Media querymedia query: a CSS rule, written @media, that applies only when the screen is narrower or wider than a given width.Look and layout: One page that fits every screen
Megabytemégaoctet, Mo: a unit of file size, written MB, often used for photos, videos and the weight of a web page.The request path: What to ask
Menumenu: a list of links or actions that you choose from, such as the main sections of a site.Components and states: The parts of a page
Micro-interactionmicro-interaction: a small designed moment around one action, such as a heart that fills when you like a song.Components and states: States
Milestonejalon: a date in the project when one part is delivered and checked, such as the mockups.The brief: Quotes, prices and who decides
Minificationminification: removing spaces and shortening names in code, so the files are smaller and load faster.Public and secret: Your copy of the page
Mobile firstmobile first: the method of designing the phone version of a page first, then adding columns as the screen gets wider.Look and layout: One page that fits every screen Layout and space: One layout for every screen
Mockupmaquette: a picture of what a page will look like, made before the site is built.Look and layout: One page that fits every screen Look and layout: What to ask Layout and space: What to ask The brief: Write the content first
Modal or dialogfenêtre modale, boîte de dialogue: a box that opens over the page and blocks it until the visitor answers or closes it.Components and states: Things that open on top of the page
Modelmodèle: the AI inside an agent that reads text and writes a reply, such as Gemini or Claude.Working with an agent: What the agent knows
Monochromemonochrome: describes a design that uses one hue only, in several tints and shades.Type and colour: Naming a colour, and contrast
Monospacechasse fixe: describes a typeface where every letter has the same width, like a typewriter.Type and colour: Typefaces and fonts
Mood boardplanche d'inspiration: one page of screenshots, photos, colours and fonts that shows the feeling a site should give.The brief: References, and why you chose them Type and colour: How to say it
MVPproduit minimum viable: a minimum viable product, the smallest version that is already useful to its visitors.The brief: What this version won't do, and when the work is done

N

navnav: the HTML element that holds a group of links for moving around a site, such as the main menu.Structure and meaning: Links and buttons do different jobs
Navigation bar or navbarbarre de navigation: the row of links to the main sections of a site, usually in the header.Components and states: The parts of a page
Network panelonglet Réseau: the part of the developer tools that lists every request a page makes, with its status and size.The request path: One request, one response
Neutralsneutres, gris: the greys of a palette, from almost white to almost black, used for text, backgrounds and borders.Type and colour: Palette and colour roles
Non-functional requirementexigence non fonctionnelle: a rule about how well the site works, such as its speed or the devices it supports.The brief: The limits
not definednot defined: an error that means a line of code uses a name the code never created, often because of a typo.When it breaks: Reading the console
nullnull: the code's word for nothing, as in "Cannot read properties of null" when a search for an element on the page found none.When it breaks: Reading the console
NumberNumber: the JavaScript instruction that turns text such as "12" into a number that can be added.When it breaks: Wrong answers with no error message

O

Obfuscationobfuscation: making code hard to read on purpose, which hides nothing, because the browser must still understand it.Public and secret: Your copy of the page
Off-brandhors charte: describes a design that doesn't fit the image an organisation wants to give.Type and colour: How to say it
Opacityopacité: how solid a colour is; at low opacity, you see what is behind it.Type and colour: Naming a colour, and contrast
Orphanorpheline: the first line of a paragraph left alone at the bottom of a column or a page.Type and colour: Line height, line length and alignment
Out of scopehors périmètre: what a version won't include, written down so that nobody builds it by mistake.The brief: What this version won't do, and when the work is done
Outside serviceservice tiers, service externe: a service from another company that does one job for a site, such as payments, sending emails or maps.Front and back: Three places where a website runs Front and back: What to ask What keeps running: When one piece stops Where data lives: Three places data can live Where data lives: What to ask

P

Packagepackage, paquet: a ready-made piece of code, with a name and a version number, that a project downloads.Working with an agent: How agents go wrong
Paddingmarge intérieure: the space inside a box, between its edge and its content.Layout and space: Margin, padding and white space
Page headeren-tête: the band at the top of every page, with the logo, the navigation and sometimes a search bar.Components and states: The parts of a page
Page languagelangue de la page: the language declared in a page's HTML, which screen readers use to choose their voice and pronunciation.Structure and meaning: Who reads the labels
Page sourcecode source de la page: the HTML exactly as the server sent it, shown when you right-click a page and choose "View page source".Behaviour: A page that changes while it's open Structure and meaning: Three layers make one page The browser's toolbox: What needs a server When it breaks: Send the content in the HTML When it breaks: What to ask Public and secret: Your copy of the page
Page titletitre de la page: the name of a page, shown in the browser tab and in search results.Structure and meaning: Who reads the labels
Page weightpoids de la page: the total size of all the files a page downloads, measured in megabytes (MB).The request path: When a site is slow in only one place The request path: What to ask
Paginationpagination: a long list split into pages, with numbered links to move from one page to the next.Layout and space: What belongs together
Pairingassociation de polices: two typefaces chosen to work together, often one for the titles and one for the text.Type and colour: Typefaces and fonts
Palettepalette: the short list of colours that a site uses, each with its role.Type and colour: Palette and colour roles
Patchpatch: a quick fix for one bug, which often adds one more thing that someone must remember.Behaviour: One place for the data
Pathchemin: the part of a web address after the domain, such as /recherche, which names one page of the site.The request path: The parts of a web address
Personapersona: an imaginary visitor with a name, a job and a goal, who represents a whole group of real visitors.The brief: Who the site is for, and what they must do
Personal datadonnées personnelles: any information about a person who can be identified, such as a name or an email address.The brief: The limits Working with an agent: What to ask Front and back: From pages to a private area Where data lives: What to ask
Pixelpixel: the unit for fixed sizes on a screen, where a typical phone screen is about 375 pixels wide.Look and layout: The visitor's own settings
Placeholdertexte indicatif: a grey hint inside an empty field, which disappears as soon as the visitor types.Components and states: Forms
Placeholder texttexte provisoire: temporary text that fills a layout until the real text arrives.The brief: Write the content first
Plan modemode plan: a setting in which the agent can read the project and propose a plan, without changing any file.Working with an agent: Plan first, then work in small steps
Pluginplugin, extension: an add-on, often made by another company, that gives a tool such as WordPress a new feature.What keeps running: A website is rented piece by piece What keeps running: What to ask
Previewaperçu: a version of the site that runs on your computer or at a private link, so you can try it before visitors do.Working with an agent: Ask for proof
Primary buttonbouton principal: the button for the main action of a screen, with the strongest look.Components and states: Components and buttons
Primary colourcouleur principale: the main brand colour of a site, used for the main buttons and the links.Type and colour: Palette and colour roles
Private windowfenêtre de navigation privée: a browser window that deletes its cookies and stored data when you close it.Where data lives: How the site knows it's you Where data lives: Without an account, the browser remembers
Progressive enhancementamélioration progressive: a way of building where the content arrives in the HTML, and scripts only add extra features.When it breaks: Send the content in the HTML
Promptconsigne, prompt: a request or an instruction that you type for the agent.Working with an agent: What the agent knows
Prototypeprototype: a first working version of a tool, made quickly to try an idea before building it properly.The browser's toolbox: What to ask
Proximityproximité: the rule that things placed close together look as if they belong together.Layout and space: What belongs together
Public feedAPI publique: data that a service publishes for any site to use, such as weather forecasts or train times.The browser's toolbox: A toolbox in every browser The browser's toolbox: Before paying for a server
Publishable keyclé publiable, clé publique: a code made to be in the page, which only tells a service which project is calling and gives no power on its own.Public and secret: Keys that are public on purpose Public and secret: What to ask
Pull quotecitation en exergue: a short sentence from the text, repeated in large type to catch the eye.Type and colour: Size, weight and the type scale

Q

Queryparamètres d'URL, query string: the part of a web address after the ?, which holds details such as the words you searched for.The request path: The parts of a web address
querySelectorquerySelector: the JavaScript instruction that finds an element on the page, as in document.querySelector("#count").Behaviour: Waiting for events
Quotaquota: a limit on how much you can use a service in a given time, such as a number of map views per day.Public and secret: Keys that are public on purpose Public and secret: What really protects the data What keeps running: Is the site broken for everyone, or only for me?
Quotedevis: a firm written offer with the price, the dates and the work included, signed before the work starts.Look and layout: One set of rules for every page Look and layout: What to ask Structure and meaning: Three layers make one page The brief: Quotes, prices and who decides Front and back: Three places where a website runs

R

Radio buttonbouton radio: a small circle for one choice among a few, where choosing one clears the others.Components and states: Forms
Ragged rightfer à gauche, drapeau: text aligned on the left, with an uneven right edge.Type and colour: Line height, line length and alignment
Rate limitlimite de requêtes, rate limit: a maximum number of requests allowed in a given time, such as 100 per hour for each user.Public and secret: A secret key in the page Public and secret: What to ask
ReactReact: a popular JavaScript tool that builds only the part of a site that runs in the browser.Front and back: Placing a tool on the map
Ready-made servicesolution clé en main, SaaS: an online tool you subscribe to instead of building one, such as a booking tool or a form service.Front and back: From pages to a private area
Redirectredirection: a response that tells the browser to go to another address, for example from http to https.The request path: One request, one response
Reduced motionréduire les animations: a system setting with which visitors ask for fewer animations, and which a well-made page respects.Look and layout: The visitor's own settings The browser's toolbox: A toolbox in every browser
Reference sitesite de référence: an existing site you show the builder, saying exactly which part of it you want.The brief: References, and why you chose them
Registrarregistrar, bureau d'enregistrement: a company that sells and renews domain names, such as OVH or Gandi.What keeps running: A website is rented piece by piece What keeps running: Is the site broken for everyone, or only for me?
remrem: a unit for sizes relative to the reader's chosen text size, so they grow when the reader chooses larger text.Look and layout: The visitor's own settings
Renderrendu: to draw the screen again from the state, so that every part that shows the data is up to date.Behaviour: One place for the data
Renewalrenouvellement: paying again for a service before it ends, such as a domain name each year, so that it keeps working.What keeps running: A website is rented piece by piece What keeps running: Before the builders leave What keeps running: What to ask
Repetitionrépétition: using the same style for every element of the same kind, such as every project card.Layout and space: What belongs together
Repositorydépôt: the project's folder, also called a repo, with all its files and the history of every saved change.Working with an agent: Inside the project Public and secret: Your copy of the page
Requestrequête: a message that a browser sends to a server to ask for a file or data, or to send it something.Behaviour: Where is a change on screen saved?The browser's toolbox: A page from the disk or from a web server The request path: One request, one response The request path: What to ask
Responseréponse: the message a server sends back for each request, made of a status code, headers and a body.The request path: One request, one response
Responsiveresponsive: describes a page that rearranges itself to fit every screen, from a small phone to a wide monitor.Look and layout: One page that fits every screen Layout and space: One layout for every screen
Restorerestaurer: to replace the current data with a backup, to recover lost data or to check that the backup works.What keeps running: Before the builders leave What keeps running: What to ask
Revertannuler un commit: to cancel a change by returning the project to the commit saved before it.Working with an agent: Plan first, then work in small steps
Revokerévoquer: to cancel a key at the service, so that it stops working for anyone who has a copy.Public and secret: A secret key in the page Public and secret: What to ask
RGAARGAA: the official French standard that says how to make a site usable by people with disabilities.Structure and meaning: Checking a page without reading code Structure and meaning: What to ask The brief: The limits
Riverlézarde: a line of white gaps running down through justified text, made by stretched spaces.Type and colour: Line height, line length and alignment
Roadmapfeuille de route: the list of what comes after the first version, in order.The brief: What this version won't do, and when the work is done

S

Sans-serifsans empattements, linéale: describes a typeface whose letters have plain ends, such as Arial or Helvetica.Type and colour: Typefaces and fonts
Saturationsaturation: how strong a colour is, from grey to vivid.Type and colour: Naming a colour, and contrast
Scanninglecture en diagonale: looking quickly over a page for what interests you, without reading every line.Layout and space: What you see first
Schemeprotocole: the start of a web address, such as https, which says how the browser and the server talk.The request path: The parts of a web address
Scopepérimètre: everything a version of the project includes, written down so that everyone agrees on it.The brief: What this version won't do, and when the work is done
Screen readerlecteur d'écran: software that reads a page aloud, so that blind people and people with poor sight can use it.Structure and meaning: Who reads the labels Structure and meaning: Words for the pictures
Scriptscript: a file of JavaScript code that a page loads, which the browser runs to change the page while it's open.Behaviour: A page that changes while it's open Behaviour: Where is a change on screen saved?When it breaks: Pages that arrive empty The request path: From address to page
Script blockerbloqueur de scripts: security software that stops scripts from running in the browser, common in large companies.When it breaks: Pages that arrive empty
Scroll depthprofondeur de défilement: how far down a page visitors go before they leave it.Layout and space: What you see first
Search barbarre de recherche: a text field for searching a site, usually with a magnifying glass icon.Components and states: Forms
Secondary buttonbouton secondaire: a more discreet button for the other actions of a screen, often with an outline.Components and states: Components and buttons
Secondary colourcouleur secondaire: a second brand colour, used less often than the primary colour.Type and colour: Palette and colour roles
Secretsecret: a value that must stay private because it gives access to an account, such as a password or a key.Working with an agent: What the agent knows
Secret keyclé secrète: a code that gives power over your account, such as sending messages or moving money, so it must stay on a server.Public and secret: A secret key in the page Public and secret: Keys that are public on purpose Public and secret: What to ask
Sectionsection: one band of a page with one subject, such as "Projects" or "Contact".Layout and space: Grids, columns and alignment
Security incidentincident de sécurité: an event where an attacker may have reached accounts or data, which the team must investigate.When it breaks: What to ask
Security rulesrègles de sécurité: rules kept at a service such as Firebase that decide who can read or change each piece of data.Public and secret: What really protects the data Public and secret: What to ask
Security updatemise à jour de sécurité: a new version of a piece of software that fixes a weakness attackers could use.What keeps running: A website is rented piece by piece What keeps running: Before the builders leave What keeps running: What to ask
Selectedsélectionné: the state of a choice that is currently on, such as the tab or the menu link of the page you're on.Components and states: States
Selectorsélecteur: the first part of a style rule, which says which elements it applies to, such as button or .buy.Look and layout: Naming each colour and size once
Semantic colourscouleurs sémantiques: colours with a fixed meaning: green for success, orange for a warning, red for an error.Type and colour: Palette and colour roles
Semantic HTMLHTML sémantique: HTML that labels each part of a page for what it is, such as a heading, a menu or a button.Structure and meaning: What to ask
Serifavec empattements: describes a typeface whose letters end in small strokes, such as Times or Garamond.Type and colour: Typefaces and fonts
Serverserveur: a computer that stays connected to the internet, sends pages to browsers and keeps the data that people share.Behaviour: Where is a change on screen saved?Behaviour: What to ask The browser's toolbox: What needs a server The browser's toolbox: Before paying for a server The browser's toolbox: What to ask When it breaks: Pages that arrive empty The request path: From address to page
Server functionfonction serveur, fonction serverless: a small piece of back-end code that the company runs, which the page can call to do one job.Public and secret: A secret key in the page
Server renderingrendu côté serveur: a way of building pages where the server creates each page when someone asks for it, with its content inside.Behaviour: What frameworks are for When it breaks: Send the content in the HTML
Server-side checkvalidation côté serveur: a check that runs on the company's server, which the visitor cannot see or change.Front and back: A check in the page is only a suggestion Front and back: What to ask
Sessionsession: the record that keeps a person logged in to a site, so that ending it logs them out.When it breaks: What to ask Where data lives: How the site knows it's you
Session cookiecookie de session: a long random code that the server gives your browser at login, and uses to recognise you on each request.Where data lives: How the site knows it's you
Shadow or elevationombre portée, élévation: a shadow under a box that makes it look raised above the page.Layout and space: Margin, padding and white space
Shared mailboxboîte mail partagée: a company email address that several people can read, such as an address for the whole web team.What keeps running: Before the builders leave
Sidebarbarre latérale: a column beside the main content, with filters, a table of contents or related links.Components and states: The parts of a page
Sign-offvalidation: a written approval that one part of the work is accepted, so the next part can start.The brief: Quotes, prices and who decides
Sitemaparborescence: the list of a site's pages and how they are organised, often drawn as a tree.The brief: Write the content first
Skeleton screenécran squelette: grey shapes shown where text and pictures will appear, while they load.Components and states: What to ask
Spacing scaleéchelle d'espacement: a short list of gap sizes, such as 4, 8, 16, 24 and 32 pixels, used everywhere on a site.Layout and space: Margin, padding and white space
Specificationcahier des charges: a long document, also called a spec, that describes every page and requirement in detail.The brief: Quotes, prices and who decides
Spending limitplafond de dépenses: a maximum amount that a service may charge you each month, which you set in your account.Public and secret: A secret key in the page Public and secret: What to ask
Spinnerindicateur de chargement, spinner: a small turning circle that tells visitors to wait.Components and states: What to ask
Squint testtest des yeux plissés: half closing your eyes in front of a page, to see which parts still stand out.Layout and space: What you see first
Stackstack technique: the list of tools behind a site, such as React for the page and Firebase for the data.Front and back: Placing a tool on the map Front and back: What to ask
Stack tracestack trace: the list of functions that were running when an error happened, shown under the error message.Working with an agent: When a step breaks something
Stackingempilement: placing blocks one under the other, as a phone does with blocks that sat side by side.Layout and space: One layout for every screen
Stakeholderpartie prenante: a person or team that the project affects and who has an opinion on it.The brief: Quotes, prices and who decides
Stateétat: the data that a page keeps in one place, such as the number of passengers, from which the screen is drawn.Behaviour: One place for the data Behaviour: What frameworks are for Behaviour: What to ask
Static hosthébergeur statique: a service, such as GitHub Pages, that sends a site's files as they are, with no code of the site running on a server.The browser's toolbox: A toolbox in every browser The browser's toolbox: Before paying for a server The browser's toolbox: A page from the disk or from a web server The browser's toolbox: What to ask
Static sitesite statique: a site made of pages built in advance from the data, which the host sends exactly as they are.When it breaks: Send the content in the HTML Front and back: From pages to a private area
Status codecode de statut, code HTTP: a three-digit number in each response that says what happened, such as 200 for success or 404 for a missing page.The request path: One request, one response
Status pagepage de statut: a public page where a service shows whether it is working now and lists its recent problems.What keeps running: Is the site broken for everyone, or only for me?
Stepperindicateur d'étapes: a line that shows the steps of a long form and where the visitor is.Components and states: Forms
Sticky headeren-tête collant: a header that stays at the top of the screen once you scroll past it.Layout and space: One layout for every screen
Stock photophoto de banque d'images: a generic photo taken from a photo library, used when no real photo exists.The brief: Write the content first
Stringchaîne de caractères: a piece of text in code, such as "12", which the + sign joins to other text instead of adding.When it breaks: Wrong answers with no error message
StripeStripe: an online payment service that many websites use to accept card payments.Public and secret: Keys that are public on purpose
Style guidecharte graphique: the document that fixes an organisation's logo, typefaces, colours and how to use them.Type and colour: How to say it
Style rulerègle CSS: an instruction in CSS that says how every element of one kind looks, such as "main buttons are blue".Look and layout: One set of rules for every page Structure and meaning: Three layers make one page
Style sheetfeuille de style: a CSS file that sets the look of a page, such as its colours, fonts and layout.The request path: From address to page
Styles panelpanneau Styles: the part of the developer tools that lists every style rule applied to the selected element, with its file.Look and layout: One set of rules for every page
SupabaseSupabase: an online service that rents you a ready-made back end, with a database, logins and file storage.Front and back: Placing a tool on the map
Surfacesurface: the colour of a box laid on the background, such as a card or a panel.Type and colour: Palette and colour roles
System fontpolice système: a typeface already installed on the visitor's device, which the page can use without downloading it.Type and colour: Typefaces and fonts
System promptprompt système: hidden instructions from the company that makes the agent, which the model reads before yours.Working with an agent: Inside the project

T

Tab keytouche Tab: the key that moves from one link, button or form field to the next, so that a page can be used without a mouse.Look and layout: The visitor's own settings Structure and meaning: Who reads the labels Structure and meaning: Checking a page without reading code
Tabletableau: items shown in rows and columns, the best way to compare numbers such as times and prices.Layout and space: What belongs together
Tabsonglets: a row of labels, each one showing a different panel in the same place.Components and states: Things that open on top of the page
Tagbalise: the marker written around content in HTML to say which element it is, such as <h1> and </h1> around a heading.Structure and meaning: Links and buttons do different jobs When it breaks: Text that becomes code
Target audiencecible: the group of people a site is made for, such as recruiters for a portfolio.The brief: Who the site is for, and what they must do
Tasktâche: one action a visitor does on a site to reach their goal, such as opening a project.The brief: Who the site is for, and what they must do
Terminalterminal: a window where you control the computer by typing text commands.Working with an agent: Inside the project
Terms of serviceconditions d'utilisation: the rules a service sets for its use, including its limits and prices, which it can change.The browser's toolbox: Before paying for a server
Test modemode test: a starting setting in Firebase that lets anyone on the internet read and change the whole database.Public and secret: What really protects the data
Text alignmentalignement du texte: where the lines of a paragraph start and end: on the left, centred, on the right or justified.Type and colour: Line height, line length and alignment
Text field or inputchamp de saisie: a box where a visitor types one line, such as a name or an email.Components and states: Forms
textContenttextContent: the JavaScript instruction that sets the text of an element, shown exactly as written, even if it contains tags.Behaviour: Waiting for events When it breaks: Text that becomes code
Third-party scriptscript tiers: a script from another company that a page loads, such as an ad, a chat window or an analytics tool.The request path: When a site is slow in only one place The request path: What to ask
Third-party serviceservice tiers: a ready-made service that another company runs, such as a form or booking tool, used instead of your own server.The browser's toolbox: What needs a server The browser's toolbox: Before paying for a server The browser's toolbox: What to ask
Throttlingthrottling, bridage réseau: a setting in the developer tools that makes the connection slow on purpose, to test a page.The request path: When a site is slow in only one place
Time and materialsrégie: a way to pay for the days actually worked, plus costs such as paid photos.The brief: Quotes, prices and who decides
Tint and shadeteinte claire, teinte foncée: a colour mixed with white, and a colour mixed with black.Type and colour: Naming a colour, and contrast
Toast or snackbarnotification éphémère, toast: a short message that appears at the edge of the screen and disappears after a few seconds.Components and states: Things that open on top of the page
Toggle or switchinterrupteur: a control that turns a setting on or off at once, such as dark mode.Components and states: Forms
Tokenjeton, token: a small piece of text, often part of a word, which a model reads and writes one at a time.Working with an agent: How agents go wrong
Tone of voiceton éditorial: the way the texts of a site sound, such as formal or friendly, serious or playful.The brief: References, and why you chose them
Tool useutilisation d'outils: the way an agent acts, by asking the editor to read a file, edit it or run a command.Working with an agent: Inside the project
Tooltipinfobulle: a small label that appears when you point at an element or reach it with the keyboard.Components and states: Things that open on top of the page
Trackertraceur, tracker: a script that records what visitors do on a site, often to show them targeted ads.The request path: When a site is slow in only one place
Transitiontransition: the short, smooth change from one state to another, such as a box that fades in.Components and states: Things that open on top of the page
Type scaleéchelle typographique: a short list of text sizes, each with a job, such as name, section title, body text and caption.Type and colour: Size, weight and the type scale
Typefacepolice de caractères: a family of letters drawn in one style, such as Helvetica or Garamond.The brief: References, and why you chose them Type and colour: Typefaces and fonts
Typofaute de frappe: a typing mistake, such as prixTotl instead of prixTotal.When it breaks: Reading the console
Typographic hierarchyhiérarchie typographique: the order of importance that sizes and weights give to the texts of a page.Type and colour: Size, weight and the type scale

U

UIinterface utilisateur: the user interface, which is everything on screen that a person sees and uses.Behaviour: One place for the data Layout and space: What to ask
UI = f(state): a short way to say that the screen is always drawn from the data, by one piece of code.Behaviour: One place for the data
Unlisted pagepage non répertoriée: a page with no link pointing to it, which anyone who has its address can still open.Front and back: From pages to a private area
Uptime monitoringmonitoring, supervision: a service that checks a site every few minutes and alerts you when it stops answering.What keeps running: Before the builders leave
User flowparcours utilisateur: the path a visitor follows through the screens to reach a goal, such as downloading a CV.Layout and space: What to ask
User goalobjectif utilisateur: the reason a visitor comes to a site, such as deciding whether to call a candidate.The brief: Who the site is for, and what they must do
User storyuser story, récit utilisateur: a requirement written from the visitor's side, such as "As a recruiter, I want to find the CV, so that I can call you."The brief: Who the site is for, and what they must do
UTM parametersparamètres UTM: labels added to the query of a link, which tell the marketing team where a visitor came from.The request path: The parts of a web address
UXexpérience utilisateur: the user experience, which is how easy and pleasant it is to use a site and reach a goal on it.Layout and space: What to ask

V

valuevalue: the text inside a form field, which reaches the script as text even when it looks like a number.When it breaks: Wrong answers with no error message
Variablevariable: a name in the code that holds a value, such as count for the number of items in the basket.Behaviour: Waiting for events When it breaks: Reading the console
Variantvariante: a version of a component for another use, such as a small button or a card without a photo.Components and states: Components and buttons
Versionversion: one numbered release of a package or a tool, such as 5.2.1, where higher numbers are newer.Working with an agent: How agents go wrong
Version 1V1, première version: the first version that goes online, with only the features chosen for it.The brief: What this version won't do, and when the work is done
Vertical rhythmrythme vertical: the regular spacing from the top of a page to the bottom, such as the same gap between sections.Layout and space: What belongs together
Viewportfenêtre d'affichage, viewport: the part of the screen where the page shows, about 375 pixels wide on most phones.Layout and space: One layout for every screen
Visual feedbackretour visuel: a visible change that answers a visitor's action, so they know that it worked.Components and states: States
Visual hierarchyhiérarchie visuelle: the order in which the eye notices the parts of a page, set by size, weight, colour, position and space.Layout and space: What you see first

W

Warm and cool colourscouleurs chaudes et froides: reds, oranges and yellows feel warm; blues, greens and purples feel cool.Type and colour: Naming a colour, and contrast
Web addressURL, adresse web: the text that leads to one page on the web, such as https://www.leboncoin.fr/recherche.The request path: The parts of a web address
Web APIAPI web: a ready-made tool built into every browser that a page's script can use, such as local storage or the camera.The browser's toolbox: A toolbox in every browser
Web fontpolice web: a typeface downloaded with the page, often from Google Fonts, so every visitor sees the same letters.Type and colour: Typefaces and fonts
Web serverserveur web: a program that sends a site's files to browsers when they ask, on the internet or on your own computer.The browser's toolbox: A page from the disk or from a web server
WebflowWebflow: a paid online service that combines a design tool, hosting and content editing in one subscription.Front and back: Placing a tool on the map
Weightgraisse: the thickness of the letters, named from light, regular and medium to semibold and bold.Type and colour: Size, weight and the type scale
White spaceespace blanc, espace négatif: all the empty space on a page, which rests the eye and groups things.Layout and space: Margin, padding and white space
Widowveuve: the last line of a paragraph left alone at the top of a column, or one word alone on a title's last line.Type and colour: Line height, line length and alignment
Wireframemaquette fil de fer, wireframe: a simple drawing of a page in grey boxes and lines, made to decide the layout before the look.Layout and space: What you see first
WordPressWordPress: a popular tool that builds pages on a server, keeps the content in a database and gives an admin screen to edit it.Front and back: Placing a tool on the map

X

X-heighthauteur d'x: the height of the small letters such as x; a large x-height stays readable at small sizes.Type and colour: Size, weight and the type scale
XSSfaille XSS: cross-site scripting, a flaw where code typed by a visitor runs in the browser of everyone who opens the page.When it breaks: Text that becomes code When it breaks: What to ask

Z

Z-orderordre de superposition: the order of the layers on a page, which decides what covers what.Layout and space: One layout for every screen
Z-patternlecture en Z: the path of the eye on a simple page: across the top, diagonally down, then across the bottom.Layout and space: What you see first