What is WCAG? The principles of the web accessibility guidelines

Summary

WCAG (Web Content Accessibility Guidelines) are internationally recognized standards for web accessibility developed by the W3C. They are based on four core principles—Perceivable, Operable, Understandable, and Robust (POUR)—and are organized into guidelines and success criteria across three levels of conformance (A, AA, AAA).

Key Takeaways

• WCAG is the global standard for web accessibility.
• It is based on four principles: Perceivable, Operable, Understandable, Robust.
• Each principle contains guidelines and measurable success criteria.
• Conformance is defined at three levels: A, AA, and AAA.
• Most organizations target Level AA compliance.

What is WCAG?

Web Content Accessibility Guidelines (WCAG) are web accessibility guidelines developed as part of the Web Accessibility Initiative (WAI) by the World Wide Web Consortium (W3C).

The guidelines are internationally recognized as the best practice worldwide.

How WCAG works

WCAG focus on four main principles:

• Perceivable
• Operable
• Understandable
• Robust

Within each of these four areas, there is a set of guidelines, and each guideline has a set of success criteria.

The individual success criteria are most commonly used for conformance requirements. 

They are divided into three levels: 

• Level A
• Level AA
• Level AAA. 

Why it matters

Most organizations are required to conform with level AA (all criteria on level A and level AA).

For further information see "Web Content Accessibility Guidelines (WCAG) Overview" from the World Wide Web Consortium (W3C).