WCAG (Web Content Accessibility Guidelines)
The international standard, published by the W3C, that defines how to make web content accessible to people with disabilities.
WCAG is the technical backbone of nearly every accessibility law, from the ADA to the EAA. It organizes requirements under four principles — Perceivable, Operable, Understandable, Robust — as testable success criteria at three levels (A, AA, AAA).
Level AA is the practical legal target. The current version is WCAG 2.2.