# Web Development glossary

105 Web Development terms, from Novice to Master. Start with the basics or jump to a level.

Updated: October 16, 2026

## Novice

- [Absolute Path](https://www.ask-codey.com/glossary/absolute-path): An absolute path is the entire path of a resource.
- [API](https://www.ask-codey.com/glossary/api): A set of rules that lets one program ask another for data or actions.
- [Browser default styles](https://www.ask-codey.com/glossary/browser-default-styles): Styles the browser adds before yours, like blue links and heading sizes.
- [Client and Server](https://www.ask-codey.com/glossary/client-and-server): The client asks; the server answers.
- [Color](https://www.ask-codey.com/glossary/color): The color property sets text color; colors can be names, hex or rgb().
- [External stylesheet](https://www.ask-codey.com/glossary/external-stylesheet): A separate .css file that pages load with a <link> tag.
- [Fragment identifier](https://www.ask-codey.com/glossary/fragment-identifier): The portion of a URL that appears after the # symbol.
- [HTTP](https://www.ask-codey.com/glossary/http): The request-and-response language of the web.
- [HTTPS](https://www.ask-codey.com/glossary/https): HTTP over an encrypted connection.
- [Inline style](https://www.ask-codey.com/glossary/inline-style): CSS written on one element with the style attribute.
- [Internal stylesheet](https://www.ask-codey.com/glossary/internal-stylesheet): CSS inside a <style> tag that styles only that page.
- [JSON](https://www.ask-codey.com/glossary/json): The text format most APIs use for data.
- [Kebab Case](https://www.ask-codey.com/glossary/kebab-case): All letters are lower case. Each word is separated by an dash.
- [Link element](https://www.ask-codey.com/glossary/link-element): This loads an external stylesheet.
- [Pixel](https://www.ask-codey.com/glossary/pixel): px: a fixed unit of size on screen.
- [Relative Path](https://www.ask-codey.com/glossary/relative-path): A relative path is where the path of a resource is defined in relation to the current…
- [Request](https://www.ask-codey.com/glossary/request): What the client sends: method, URL, headers and an optional body.
- [Response](https://www.ask-codey.com/glossary/response-web-development): What the server sends back: a status code, headers and usually a body.
- [URL](https://www.ask-codey.com/glossary/url): The full address of a resource on the web.
- [Web API](https://www.ask-codey.com/glossary/web-api): An API you call over HTTP, usually getting JSON back.

## Apprentice

- [200 OK](https://www.ask-codey.com/glossary/200-ok): The request worked and the body holds the result.
- [201 Created](https://www.ask-codey.com/glossary/201-created): A new resource was created.
- [204 No Content](https://www.ask-codey.com/glossary/204-no-content): It worked and there is no body to return.
- [400 Bad Request](https://www.ask-codey.com/glossary/400-bad-request): The request is invalid, such as a missing or wrong field.
- [401 Unauthorized](https://www.ask-codey.com/glossary/401-unauthorized): No valid credentials were sent: sign in first.
- [403 Forbidden](https://www.ask-codey.com/glossary/403-forbidden): Signed in, but not allowed to do this.
- [404 Not Found](https://www.ask-codey.com/glossary/404-not-found): Nothing exists at that URL.
- [500 Internal Server Error](https://www.ask-codey.com/glossary/500-internal-server-error): Something broke on the server.
- [Content-Type](https://www.ask-codey.com/glossary/content-type): The header that says what format a body is in.
- [DELETE (HTTP)](https://www.ask-codey.com/glossary/delete-http): The method that removes a resource.
- [GET](https://www.ask-codey.com/glossary/get): The method that reads data without changing anything.
- [Header](https://www.ask-codey.com/glossary/header-web-development): A name-value line of extra information on a request or response.
- [HTTP Method](https://www.ask-codey.com/glossary/http-method): The verb that says what a request wants to do.
- [PATCH](https://www.ask-codey.com/glossary/patch-web-development): The method that updates only some fields of a resource.
- [POST](https://www.ask-codey.com/glossary/post): The method that creates a new resource.
- [POST form submission](https://www.ask-codey.com/glossary/post-form-submission): A form submission that sends form data in the request body.
- [PUT](https://www.ask-codey.com/glossary/put): The method that replaces a whole resource.
- [Query String](https://www.ask-codey.com/glossary/query-string): The ?key=value part of a URL, used for filters and paging.
- [Request Body](https://www.ask-codey.com/glossary/request-body-web-development): The data sent with a request, usually JSON.
- [Status Code](https://www.ask-codey.com/glossary/status-code): The three-digit result number: 2xx success, 4xx client error, 5xx server error.
- [Viewport](https://www.ask-codey.com/glossary/viewport): The visible area of the page; vw and vh measure it.

## Journeyman

- [409 Conflict](https://www.ask-codey.com/glossary/409-conflict): The request clashes with the current state, like a duplicate.
- [422 Unprocessable Content](https://www.ask-codey.com/glossary/422-unprocessable-content): Well-formed data whose values break the rules.
- [429 Too Many Requests](https://www.ask-codey.com/glossary/429-too-many-requests): You sent too many requests; wait and try again.
- [aria-hidden](https://www.ask-codey.com/glossary/aria-hidden): An ARIA attribute that removes an element and its descendants from the accessibility tree when true.
- [aria-label](https://www.ask-codey.com/glossary/aria-label): An ARIA attribute that supplies an accessible name as a text value.
- [aria-labelledby](https://www.ask-codey.com/glossary/aria-labelledby): An ARIA attribute that uses other elements' text to form an accessible name.
- [Art direction](https://www.ask-codey.com/glossary/art-direction): Providing differently composed or cropped images for different presentation conditions.
- [Authentication](https://www.ask-codey.com/glossary/authentication): Proving who you are.
- [Authorization](https://www.ask-codey.com/glossary/authorization): Deciding what an identified user is allowed to do.
- [Breakpoint](https://www.ask-codey.com/glossary/breakpoint): A screen width where the layout changes.
- [Canonical link](https://www.ask-codey.com/glossary/canonical-link): A link identifying the preferred URL for content available through multiple URLs.
- [Character encoding declaration](https://www.ask-codey.com/glossary/character-encoding-declaration): Markup near the start of a document that declares its text encoding as UTF-8.
- [Cookie](https://www.ask-codey.com/glossary/cookie): Small data the browser stores and sends back to the same site on every request.
- [CORS](https://www.ask-codey.com/glossary/cors): Server rules that tell browsers which other sites may call it.
- [Document language](https://www.ask-codey.com/glossary/document-language): The primary human language of a document or element's text.
- [Favicon](https://www.ask-codey.com/glossary/favicon): An icon associated with a website or page for browser tabs, bookmarks, and similar interfaces.
- [JWT](https://www.ask-codey.com/glossary/jwt): A signed token carrying who the user is and when it expires.
- [Lazy loading](https://www.ask-codey.com/glossary/lazy-loading): Delaying an off-screen resource until it is likely to be needed.
- [Location Header](https://www.ask-codey.com/glossary/location-header): A header pointing to a new resource or a redirect target.
- [Media query](https://www.ask-codey.com/glossary/media-query): Applies CSS only when a condition is true, like a minimum screen width.
- [Meta description](https://www.ask-codey.com/glossary/meta-description): A short document summary supplied as metadata, often used by search and sharing tools.
- [Mobile-first design](https://www.ask-codey.com/glossary/mobile-first-design): Phone layout first, then media queries for bigger screens.
- [noopener](https://www.ask-codey.com/glossary/noopener): A link relationship that prevents a newly opened page from receiving an opener reference.
- [noreferrer](https://www.ask-codey.com/glossary/noreferrer): A link relationship that omits referrer information and also prevents an opener relationship.
- [prefers-color-scheme](https://www.ask-codey.com/glossary/prefers-color-scheme): Checks whether the user prefers a light or dark theme.
- [prefers-reduced-motion](https://www.ask-codey.com/glossary/prefers-reduced-motion): Checks whether the user asked for less animation.
- [Responsive design](https://www.ask-codey.com/glossary/responsive-design): One page that adapts its layout to any screen size.
- [Responsive image](https://www.ask-codey.com/glossary/responsive-image): An image setup that lets the browser select a suitable resource for the display and layout.
- [Safe Method](https://www.ask-codey.com/glossary/safe-method): A method that only reads and never changes data, like GET.
- [tabindex](https://www.ask-codey.com/glossary/tabindex): A global attribute that controls whether and where an element participates in sequential focus navigation.
- [Text direction](https://www.ask-codey.com/glossary/text-direction): The direction in which text and inline content progress.
- [Viewport metadata](https://www.ask-codey.com/glossary/viewport-metadata): Metadata that guides how a page's viewport is sized and scaled on mobile devices.

## Freelancer

- [Caching Headers](https://www.ask-codey.com/glossary/caching-headers): Headers that say how long a response may be reused.
- [Conditional Request](https://www.ask-codey.com/glossary/conditional-request): A request that only proceeds if the resource is still in the expected state.
- [Content Negotiation](https://www.ask-codey.com/glossary/content-negotiation): The client asks for a format with Accept; the server picks one it supports.
- [crossorigin](https://www.ask-codey.com/glossary/crossorigin): An attribute that configures a cross-origin request and whether credentials are included.
- [ETag](https://www.ask-codey.com/glossary/etag): A version fingerprint that lets clients skip downloading unchanged data.
- [Focusable area](https://www.ask-codey.com/glossary/focusable-area): A page region or control that can become the target of keyboard focus.
- [Iframe sandbox](https://www.ask-codey.com/glossary/iframe-sandbox): Restrictions applied to content in an iframe through its sandbox attribute.
- [Light dismiss](https://www.ask-codey.com/glossary/light-dismiss): Closing a temporary interface by interacting outside it or making a platform close request.
- [Multipart form data](https://www.ask-codey.com/glossary/multipart-form-data): A form encoding that separates entries into parts and supports file uploads.
- [nonce attribute](https://www.ask-codey.com/glossary/nonce-attribute): A one-use token that a Content Security Policy can require on allowed inline script or style elements.
- [OAuth 2.0](https://www.ask-codey.com/glossary/oauth-2-0): A standard for granting apps limited access via tokens instead of passwords.
- [OpenID Connect](https://www.ask-codey.com/glossary/openid-connect): Sign-in built on OAuth 2.0; used by "Sign in with Google".
- [Preflight Request](https://www.ask-codey.com/glossary/preflight-request): The OPTIONS check a browser sends before some cross-origin requests.
- [referrerpolicy](https://www.ask-codey.com/glossary/referrerpolicy): An attribute that controls which referrer information is sent when fetching or navigating.
- [Refresh Token](https://www.ask-codey.com/glossary/refresh-token): A long-lived token used to get new short-lived access tokens.
- [Sequential focus navigation](https://www.ask-codey.com/glossary/sequential-focus-navigation): Moving focus through eligible page controls in an ordered sequence, commonly with the Tab key.
- [Subresource integrity](https://www.ask-codey.com/glossary/subresource-integrity): A security feature that checks a fetched resource against an expected cryptographic hash.
- [URL-encoded form data](https://www.ask-codey.com/glossary/url-encoded-form-data): A form encoding that represents name-and-value pairs using URL-style escaping.

## Master

- [Compositing](https://www.ask-codey.com/glossary/compositing): Combining painted layers into the final picture.
- [Critical CSS](https://www.ask-codey.com/glossary/critical-css): The styles needed for the first screen, inlined so it shows fast.
- [CSS Object Model](https://www.ask-codey.com/glossary/css-object-model): The browser's in-memory model of the page's CSS, readable from JavaScript.
- [HTML parser](https://www.ask-codey.com/glossary/html-parser): The browser component that turns HTML source into a document tree.
- [HTTP/2 and HTTP/3](https://www.ask-codey.com/glossary/http-2-and-http-3): Newer HTTP versions that send many requests at once over one connection.
- [Layout](https://www.ask-codey.com/glossary/layout): The step where the browser works out every box's size and position.
- [MathML namespace](https://www.ask-codey.com/glossary/mathml-namespace): The namespace URI that identifies inline MathML elements in a document tree.
- [Mutual TLS](https://www.ask-codey.com/glossary/mutual-tls): Both client and server present certificates to prove who they are.
- [Reflow](https://www.ask-codey.com/glossary/reflow): The browser redoing layout after a size or position change.
- [Repaint](https://www.ask-codey.com/glossary/repaint): Redrawing pixels after a look changes, without a size change.
- [Server-Sent Events](https://www.ask-codey.com/glossary/server-sent-events): A response kept open so the server can push a stream of events.
- [Style invalidation](https://www.ask-codey.com/glossary/style-invalidation): Working out which elements need styles recalculated after a change.
- [SVG namespace](https://www.ask-codey.com/glossary/svg-namespace): The namespace URI that identifies inline SVG elements in a document tree.
- [text/html MIME type](https://www.ask-codey.com/glossary/text-html-mime-type): The media type that identifies a resource as an HTML document parsed with HTML syntax.

[More subjects in Web Basics](https://www.ask-codey.com/glossary/groups/web-basics)

Source: https://www.ask-codey.com/glossary/subjects/web-development