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What is WCAG?

April 25, 2021 | Accessibility

'Web Content Accessibility Guidelines (WCAG) is developed through the W3C process in cooperation with individuals and organizations around the world, with a goal of providing a single shared standard for web content accessibility that meets the needs of individuals, organizations, and governments internationally.

The WCAG documents explain how to make web content more accessible to people with disabilities. Web “content” generally refers to the information in a web page or web application, including:

  • natural information such as text, images, and sounds
  • code or markup that defines structure, presentation, etc.
The W3C Web Accessibility Initiative (WAI)

Who is WCAG intended for?

WCAG is primarily intended for:

  • Web content developers (page authors, site designers, etc.)
  • Web authoring tool developers
  • Web accessibility evaluation tool developers
  • Others who want or need a standard for web accessibility, including for mobile accessibility

WCAG versions

WCAG 2.0 was published on 11 December 2008. WCAG 2.1 was published on 5 June 2018 and it's the current version in the law. WCAG 2.2 is scheduled to be published in 2021. Read more about the WCAG 2.2 draft.

All requirements in 2.0 are included in 2.1. And now all requirements in 2.0 and 2.1 will be included in 2.2. The wording of the 2.0 and 2.1 success criteria will be exactly the same in 2.2.

WCAG guideline categories

WCAG guidelines are categorized into three levels of conformance in order to meet the needs of different groups and different situations: A (lowest), AA (mid-range), and AAA (highest). Conformance at higher levels indicates conformance at lower levels. Level AA is the level that is legally required for certain sites.

WCAG guidelines are organized under four principles: perceivable, operable, understandable, and robust (often referred to with the acronym POUR).

If any of these following principles are not true, users with disabilities will not be able to use the Web properly.


Information and user interface components must be presentable to users in ways they can perceive.

This means that users must be able to perceive the information being presented (it can't be invisible to all of their senses)


User interface components and navigation must be operable.

This means that users must be able to operate the interface (the interface cannot require interaction that a user cannot perform)


Information and the operation of the user interface must be understandable.

This means that users must be able to understand the information as well as the operation of the user interface (the content or operation cannot be beyond their understanding)


Content must be robust enough that it can be interpreted reliably by a wide variety of user agents, including assistive technologies.

This means that users must be able to access the content as technologies advance (as technologies and user agents evolve, the content should remain accessible)

Learn more about accessibility and WCAG

There is a free course on edX: Introduction to Web Accessibility
The course has a lot of good information about accessibility. You can also get a verified certificate, at the time of writing that costs 84 euros.

Check out my accessibility site for various information and resources I've collected on accessibility.

Sources and more information: