A curated resource guide covering the legal landscape, technical standards, official guidance, and practical references for WCAG 2.1 AA compliance.
WCAG organizes every requirement under four principles, collectively known as POUR. Every success criterion in the standard traces back to one of these four roots:
These are the criteria most frequently cited in ADA complaints, audit findings, and litigation. The SC (success criterion) number maps directly to the WCAG specification.
| SC | Name | What it requires |
|---|---|---|
| 1.1.1 | Non-text Content | All images, icons, and non-text UI elements must have a text alternative (alt text). Decorative images must be hidden from assistive technology. |
| 1.3.1 | Info & Relationships | Structure conveyed visually (headings, lists, labels) must also be conveyed programmatically — correct HTML elements and ARIA roles. |
| 1.4.3 | Contrast (Minimum) | Normal text must achieve 4.5:1 contrast ratio against its background. Large text (18pt+) requires 3:1. This is one of the most common failures. |
| 1.4.4 | Resize Text | Text must be resizable up to 200% without loss of content or functionality. Viewport user-scalable=no is a violation. |
| 2.1.1 | Keyboard | All functionality available by mouse must also be available by keyboard alone. No keyboard traps. |
| 2.4.1 | Bypass Blocks | A mechanism must exist to skip repeated navigation blocks — typically a "skip to main content" link. |
| 2.4.3 | Focus Order | Focus order must be logical and preserve meaning. Keyboard tab sequence must follow reading order. |
| 2.4.6 | Headings & Labels | Headings and labels must describe their topic or purpose. Heading hierarchy (h1→h2→h3) must be semantically correct — one of the most common audit findings. |
| 3.1.1 | Language of Page | The default human language of the page must be programmatically determinable — lang attribute on the HTML element. |
| 4.1.2 | Name, Role, Value | For all UI components, name and role must be programmatically determinable. States, properties, and values must be set and updated. The foundation of correct ARIA use. |
| 4.1.3 | Status Messages | Status messages — errors, alerts, loading indicators — must be determinable by assistive technology without receiving focus. |
These are the operational steps required to achieve and maintain WCAG 2.1 AA conformance — not just as a one-time project, but as an ongoing practice.