Accessibility tree
AccessibilityDefined term
Browsers do not hand screen readers the DOM. They compute an accessibility tree: a parallel structure of accessible objects with a role, a name, a state, and properties, derived from native HTML semantics, CSS visibility, and any ARIA attributes, then exposed through platform accessibility APIs.
Whatever is absent from this tree does not exist for assistive technology. A visually obvious button rendered from bare divs with no role and no accessible name is, to a screen reader, silence — which is why WCAG conformance is ultimately a contract about what this tree contains.
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Accessibility6 of 28 terms
- Accessibility treeThe parallel structure a browser derives from DOM, CSS, and ARIA that assistive technology actually reads.Accessibility
- Accessible nameThe single text label assistive technology announces for an element, computed by a W3C-specified algorithm.Accessibility
- Focus orderThe sequence keyboard focus follows through interactive elements — WCAG requires it to preserve meaning and operability.Accessibility
- ARIA roleThe WAI-ARIA attribute that declares what an element is to assistive technology — a promise of behavior, not a behavior.Accessibility
- Assistive technology (AT)Software and hardware — screen readers, magnifiers, switch devices — that consume the accessibility tree to operate interfaces.Accessibility
- Contrast ratio⦿ liveThe WCAG-defined luminance ratio between text and background: 4.5:1 minimum for body text at level AA.Accessibility