WCAG

WCAG, the Web Content Accessibility Guidelines, is the international standard for making web content accessible to people with disabilities. Published by the W3C, the guidelines are organized around four principles: content must be Perceivable, Operable, Understandable, and Robust. These four principles are abbreviated as POUR.

Each principle breaks down into specific success criteria with three conformance levels: A (minimum), AA (standard), and AAA (enhanced). Level AA is the target for most organizations since it covers the most impactful requirements without the strictest constraints of AAA. Requirements at AA include sufficient text contrast (4.5:1 for normal text), keyboard accessibility, descriptive page titles, error identification in forms, and text alternatives for non-text content.

WCAG 2.1, released in 2018, added criteria for mobile, low vision users, and cognitive disabilities. WCAG 2.2, published in 2023, added focus appearance requirements and refined several existing criteria. WCAG 3.0 is in development and proposes a more flexible scoring model, though it will not replace WCAG 2.x for years. Organizations implementing accessibility today should target WCAG 2.1 AA at minimum.

Legal weight behind WCAG varies by country. In the United States, courts have widely interpreted the ADA as applying to websites, and WCAG 2.1 AA is the de facto standard referenced in settlement agreements. The European Accessibility Act requires conformance for businesses selling to EU customers from 2025. Treating WCAG as a compliance checklist misses the point -- the underlying goal is ensuring real people can use what you build.