The document discusses the Accessible Rich Internet Applications (ARIA) specification which defines ways to make web content and applications more accessible to users of assistive technologies through the use of roles, states, and properties. It provides examples of how ARIA is implemented using markup to identify document structure and interactive elements, and explains how ARIA works together with HTML5 to semantically enrich content while preventing too much information from being conveyed to assistive technology users. ARIA takes precedence over conflicting HTML5 semantics to optimize for the best user experience for those using assistive technologies.