Accessibility tree

The accessibility tree is the simplified version of a page that a browser builds for assistive technology. It contains each element's role, name, and state, but not its visual styling. If information is missing or wrong in the accessibility tree, a screen reader cannot present it, no matter how the page looks.

The browser builds the accessibility tree from the DOM, using each element's native semantics plus any ARIA attributes that override or add to them - which is why the accessibility tree is the layer most accessibility bugs actually live in, even when the visible page and the raw HTML both look correct.

Learn more

• Core Accessibility API Mappings (Core-AAM) 1.2 - the W3C specification defining how content maps to the accessibility tree
• Accessibility tree - MDN's approachable explanation
• DOM
• ARIA