Accessibility tree
The accessibility tree is the structure a browser exposes to assistive technology, derived from the DOM but not identical to it.
Open resourceShared vocabulary
Web terms in practical context
Definitions link to standards and to the work where each idea matters.
Accessible name
An accessible name is the text alternative by which assistive technology identifies a user-interface element.
Open resourceAlternative text
Alternative text replaces the purpose or information an image contributes when that image cannot be seen or loaded.
Open resourceARIA roles and states
ARIA is a set of roles, states, and properties that describe interface semantics to assistive technology when native HTML cannot.
Open resourceAssistive technology
Assistive technology is any tool a person uses to operate a page: screen readers, magnifiers, switch devices, and voice control among them.
Open resourceHTML attribute
An HTML attribute adds a name-value setting or state to an element, such as a link destination or document language.
Open resourceBox model
The box model describes how content, padding, border, and margin combine to produce the space an element occupies.
Open resourceBreakpoint
A breakpoint is the viewport condition at which a layout changes, expressed with a media query or a container query.
Open resourceCanonical URL
A canonical URL is the single address you nominate as the authoritative version of a page when several addresses serve the same content.
Open resourceCSS cascade
The CSS cascade is the ordered process browsers use to choose a winning declaration when several rules assign the same property.
Open resourceHTML doctype
The doctype is the first line of an HTML document, and its only job is to keep the browser in standards mode.
Open resourceDocument Object Model
The Document Object Model is the browser-created tree and programming interface representing a parsed HTML document.
Open resourceHTML element
An HTML element represents structure or meaning in a document and is identified by its tag name and permitted content.
Open resourceEvent listener
An event listener is a callback registered on an EventTarget to respond when a named browser, user, or application event is dispatched.
Open resourceFavicon (site icon)
A favicon is the small icon a browser shows for your site in tabs, bookmarks, and history, declared with a link element in the head.
Open resourceFocus indicator
A focus indicator is the visible styling that shows which interactive element currently receives keyboard input.
Open resourceFocus order
Focus order is the sequence in which interactive elements receive keyboard focus, normally following the document and task order.
Open resourceHTTPS connection
HTTPS is HTTP carried through an authenticated encrypted connection, giving a web origin transport confidentiality and integrity.
Open resourceCSS inheritance
CSS inheritance lets selected properties take the computed value of a parent when no declaration supplies a value on the child.
Open resourceAccessibility landmark
A landmark is a named page region that helps assistive-technology users navigate between major responsibilities such as navigation and main content.
Open resourceMedia query
A media query conditionally applies CSS or selects resources according to media type and features such as width, motion, contrast, or input capability.
Open resourceMeta description
A meta description is a short summary in the document head that search engines may use as the snippet beneath a result.
Open resourceProgressive enhancement model
Progressive enhancement starts with a useful resilient baseline, then adds presentation and behavior without making access depend on every enhancement.
Open resourceContent reflow
Reflow is the rearrangement of content to fit available width so ordinary reading and operation do not require two-dimensional scrolling.
Open resourceRender-blocking resource
A render-blocking resource delays when a browser can present page content, commonly because critical CSS or synchronous script must be processed first.
Open resourceThe robots.txt file
robots.txt is a file at your site root that tells crawlers which paths to request. It controls crawling, not indexing.
Open resourceScreen reader
A screen reader is software that presents the accessibility tree as speech or braille and lets a person navigate a page structurally.
Open resourceSemantic HTML
Semantic HTML uses elements according to their defined meaning so document structure and interactions remain understandable.
Open resourceXML sitemap
A sitemap is an XML file listing the canonical URLs you want discovered, offered to search engines as a crawl hint rather than a guarantee.
Open resourceSource order
Source order is the sequence of elements in the document, which normally drives reading order, keyboard order, and the no-CSS experience.
Open resourceSpecificity
Specificity is the weighting a browser uses to decide which CSS declaration wins when several selectors target the same element.
Open resourceStatic site
A static site serves prebuilt files or generated responses without requiring per-request application rendering for its public pages.
Open resourceStructured data
Structured data is machine-readable markup that describes what a page means, usually expressed as JSON-LD using the schema.org vocabulary.
Open resourceViewport
The viewport is the browser area through which a document is laid out and viewed, expressed in CSS pixels for responsive design.
Open resourceWCAG accessibility guidelines
WCAG is the W3C standard defining testable success criteria for web accessibility, organized under four principles and three conformance levels.
Open resource