WCAG
Also known as: Web Content Accessibility Guidelines
WCAG (Web Content Accessibility Guidelines) is the internationally recognized standard defining how to make web content accessible to people with disabilities, organized around four principles — Perceivable, Operable, Understandable, Robust — and three conformance levels (A, AA, AAA). Most legal and organizational accessibility requirements, including the ADA and Section 508, reference WCAG 2.1 or 2.2 Level AA as the practical bar.
WCAG's four principles (often abbreviated POUR) organize dozens of specific success criteria: Perceivable (can users perceive the content — alt text, captions, sufficient color contrast), Operable (can they navigate and interact — full keyboard access, no seizure-inducing flashing), Understandable (is the content and interface predictable and readable), and Robust (does it work with assistive technologies like screen readers, now and as they evolve).
Level A is the minimum viable accessibility; AA is what almost every organization actually targets, and what most accessibility laws point to; AAA is the strictest level and often impractical to apply site-wide — WCAG itself notes AAA isn't recommended as a general policy for entire sites.
Testing against WCAG combines automated scanning (catches roughly 30-40% of issues — missing alt text, insufficient contrast, missing form labels) with manual testing (keyboard-only navigation, actual screen reader testing with tools like NVDA or VoiceOver). Automation alone consistently misses the issues that matter most to real assistive-technology users.
