Understanding WCAG

The four principles

The Web Content Accessibility Guidelines (WCAG) organize requirements around four principles, often abbreviated POUR.

• Perceivable: provide text alternatives, accessible media, meaningful structure, and distinguishable information.
• Operable: support keyboard use, navigation, sufficient time, and different input methods; avoid unsafe flashing.
• Understandable: make language, interactions, instructions, and error handling understandable.
• Robust: expose information that browsers and assistive technologies can interpret reliably.

Official guidance: WCAG 2.2

Versions and conformance levels

WCAG 2.0, 2.1, and 2.2 are versions of the standard. A legal requirement or contract may name a particular version. A newer organizational design target does not remove the need to evaluate the named requirement.

• Level A: addresses foundational barriers.
• Level AA: includes Level A plus additional requirements. This site recommends WCAG 2.2 AA as a design target.
• Level AAA: adds further requirements. Individual AAA practices can improve an experience even when a whole-site AAA claim is not appropriate.

Official guidance: Understanding conformance

The 13 guideline areas

• Text alternatives for non-text information.
• Time-based media, including captions and description.
• Adaptable structure and meaningful reading order.
• Distinguishable text, graphics, and audio.
• Keyboard access.
• Enough time to read and act.
• Protection from seizures and harmful physical reactions.
• Navigation and orientation.
• Different input methods and modalities.
• Readable and understandable language.
• Predictable behavior.
• Input assistance and error prevention.
• Compatibility with assistive technologies.

Each area contains testable success criteria. Use the official quick reference to filter by version, level, and technology and to read the exact requirements and exceptions.

Official guidance: Complete WCAG quick reference

Important additions in WCAG 2.2

• Focus not obscured: author-created overlays must not entirely hide a focused component at AA.
• Dragging: provide a single-pointer alternative when dragging is not essential.
• Target size: the AA minimum is generally 24 by 24 CSS pixels, with spacing and other specified exceptions.
• Consistent help: repeated help mechanisms appear in a consistent relative order.
• Redundant entry: avoid asking users to re-enter information already provided in the same process, subject to exceptions.
• Accessible authentication: support methods that do not depend on a cognitive function test without an allowed alternative or assistance.

Official guidance: What is new in WCAG 2.2

Beyond web pages

WCAG2ICT explains how WCAG principles and criteria can be applied to non-web documents and software. It is informative guidance, not a separate certification or law. Hardware, kiosks, and closed systems may need additional provisions.

Official guidance: WCAG2ICT overview

How to use a criterion

Read the normative requirement, identify whether it applies, review its exceptions, and test the actual user experience. Record the version and level being evaluated. Techniques show ways to satisfy criteria; they are not the only possible implementations.

A meaningful evaluation includes representative pages, different states, error handling, and complete tasks. Learn how to test and document results.