ARIA in HTML

This specification defines the authoring rules (author conformance requirements) for the use of Accessible Rich Internet Applications (WAI-ARIA) 1.2 and Digital Publishing WAI-ARIA Module 1.0 attributes on [HTML] elements. This specification's primary objective is to define requirements for use with conformance checking tools used by authors (i.e., web developers). These requirements will aid authors in their development of web content, including custom interfaces and widgets, which make use of ARIA to complement or extend the features of the host language [HTML].

www.w3.org