Web, documents and technology
Accessibility tree
In short and in plain language
The accessibility tree is a version of the web page for helper programs.
The browser builds it from the code. A screen reader reads it.
It says what each part is and what it is called. If something is missing there, you do not hear it.
Definition
The accessibility tree is the version of a web page that the browser provides to assistive technologies such as screen readers. It contains information such as the role, name and state of the page's elements. Whatever is missing or wrong there does not reach the screen reader, or reaches it incorrectly.