Web Accessibility Glossary
Find definitions of key web accessibility terms: ARIA attributes, standards (WCAG, RGAA), assistive technologies, and inclusive design best practices. Each term is explained simply to help you understand and improve your site’s accessibility.
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Accessibility audit
An accessibility audit is a systematic evaluation of a website or web application against a standard (WCAG, RGAA).
Accessibility tree
The accessibility tree is a simplified representation of the DOM built by the browser, exposing only information relevant to assistive technologies: name, role, state, and value of each element.
Accessible name
The accessible name is the text string computed by the browser to identify an interactive element to assistive technologies.
Alt attribute (alternative text)
The alt attribute provides a text description of an image, allowing screen readers to convey its content to blind users.
ARIA role (role attribute)
The role attribute specifies the semantic function of an HTML element to assistive technologies, complementing or overriding native semantics.
aria-describedby
The aria-describedby attribute links an element to one or more other elements providing a supplementary description.
aria-expanded
The aria-expanded attribute indicates whether an element controlling a collapsible panel (accordion, dropdown menu, sub-navigation) is currently open (true) or closed (false).
aria-hidden
The aria-hidden="true" attribute removes an element and all its descendants from the accessibility tree, making it invisible to assistive technologies.
aria-label
The aria-label attribute defines an accessible name as a text string directly in the HTML code, without it being visible on screen.
aria-labelledby
The aria-labelledby attribute associates an element with one or more other DOM elements whose text content will serve as the accessible name.
aria-live
The aria-live attribute defines a page region whose dynamic updates must be automatically announced by assistive technologies.
Assistive technology
An assistive technology is any software or hardware that enables people with disabilities to use a computer or mobile device.
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Conformance (accessibility)
Accessibility conformance refers to meeting all criteria of a standard like WCAG or RGAA for a representative sample of pages.
Contrast (contrast ratio)
The contrast ratio measures the difference in luminance between the text color and the background color, expressed as a ratio (e.g.
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Keyboard navigation
Keyboard navigation refers to the ability to browse and interact with all website functionalities without using a mouse.
Keyboard trap
A keyboard trap occurs when a user navigating by keyboard can no longer leave a component (video player, custom widget, iframe) using only the Tab or Escape keys.
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Reflow (content redistribution)
Reflow refers to the ability of a web page to redistribute its content to remain readable when the user zooms up to 400% without generating a horizontal scrollbar.
RGAA (General Accessibility Improvement Framework)
The RGAA is the French digital accessibility framework, mandatory for public services and being extended to the private sector via the European Accessibility Act.
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Screen reader
A screen reader is software that interprets the content displayed on screen and renders it as speech or braille output.
Skip link
A skip link is an internal link placed at the very beginning of the page, usually visually hidden but keyboard-accessible, that allows jumping directly to the main content.
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WAI-ARIA
WAI-ARIA (Web Accessibility Initiative - Accessible Rich Internet Applications) is a W3C specification that defines additional HTML attributes to make dynamic web interfaces accessible.
WCAG (Web Content Accessibility Guidelines)
WCAG are the international web accessibility guidelines published by the W3C (WAI).
Validated against 9 official RGAA audits (2024–2025)
average deviation
concordance
criteria tested
Frequently Asked Questions
What is WCAG?
What is the difference between WCAG and RGAA?
What does 'non-compliance' mean in an accessibility audit?
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