Advanced HTML and Accessibility

Accessibility isn't optional—it's a requirement for inclusive products. This guide covers WCAG compliance, when and how to use ARIA, building accessible forms, focus management, testing strategies, and tools that help you catch issues early.

WCAG Guidelines Overview

Conformance Levels: A, AA, AAA

The Web Content Accessibility Guidelines (WCAG) define three conformance levels. Level A is the minimum—sites must meet these to avoid major barriers. Level AA is the target for most projects and often mandated by regulation; it includes color contrast ratios and keyboard access. Level AAA is the highest standard—more rigorous but often impractical for everything (e.g., sign language for video).

Key Principles: Perceivable, Operable, Understandable, Robust

WCAG organizes criteria under four principles. Perceivable: content must be presentable to users in ways they can perceive (text alternatives, captions, adaptable layout). Operable: interface components must be operable (keyboard access, sufficient time, no seizure-inducing content). Understandable: content and operation must be understandable (readable text, predictable behavior, input assistance). Robust: content must be robust enough for assistive technologies (valid markup, proper semantics).

ARIA Attributes and When to Use Them

ARIA Roles, States, and Properties