WCAG (Web Content Accessibility Guidelines)

WCAG and web accessibility


When discussing website accessibility, the most common term you may hear is WCAG.


The Web Content Accessibility Guidelines (WCAG) were established with global input from a wide range of international organizations known as the World Wide Web Consortium, or W3C. The goal was to provide a single, common, global standard for web accessibility. WCAG itself is not a piece of legislation but it is referenced in numerous pieces of legislation around the world, and has become the international standard for web accessibility. For example, Section 508, and the AODA evaluate accessibility against WCAG 2.0 Level A and AA success criteria (more on the WCAG conformance levels below). Since WCAG isn’t legislation, following its guidelines is called “WCAG conformance” instead of “WCAG compliance.” Legal compliance with most global regulations requires conformance with WCAG standards.


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WCAG Principles

WCAG guidelines are based on four principles (often referred to as POUR):

  • Perceivable = Information and user interface components must be presented to users in ways that they can perceive. For example, it’s important to present information that can be perceived in different ways, where a user can adjust color contrast or font size, or view captions for videos.
  • Operable = User interface components and navigation must be operable to users in ways they can operate. For example, required interactions can be performed using keyboard or voice commands.
  • Understandable = Information and user interface operation must be understandable. For example, information and instructions are clear and navigation methods are easy to understand and use.
  • Robust = Content must be robust enough so that it can be interpreted reliably by a wide variety of users and types of assistive technologies. As technologies evolve, code and content should remain accessible for users of common and current assistive devices and tools.

WCAG Conformance Levels

There are three levels of WCAG conformance: A, AA, and AAA. Level A refers to the lowest level of conformance (minimum) and Level AAA is the highest (maximum):

  • Level A = minimum WCAG conformance has been met, with web page and content satisfying all Level A success criteria (or a conforming alternate version is provided)
  • Level AA = the web page satisfies all WCAG Level A and Level AA Success Criteria (or a Level AA conforming alternate version is provided)
  • Level AAA = the web page satisfies all the Level A, Level AA and Level AAA Success Criteria (or a Level AAA conforming alternate version is provided)

Most web accessibility legislation requires WCAG 2.0 conformance of Level A or Level AA. A higher standard often relates to the size or type of an organization and includes consideration of the purpose of the website and its typical users. For example, large government websites for the general public are expected to meet the highest accessibility standards, particularly on pages where essential information or functions are included.

It is typically not recommended that Level AAA conformance be required as a general policy for entire sites because it is not possible to satisfy all Level AAA success criteria for some content, such as maps and older scanned documents.

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Frequently asked questions

Is WCAG a legal requirement?

The Web Content Accessibility Guidelines (WCAG) are not a law. However, some laws, including Section 508 of the Rehabilitation Act of 1973 and the AODA explicitly cite WCAG conformance as an accessibility requirement. Furthermore, the Department of Justice has referenced WCAG standards in its web accessibility enforcement actions. WCAG is considered the global gold standard for web accessibility, so even though WCAG conformance is not a law, following WCAG standards is the most effective way to achieve web accessibility and comply with certain legal mandates.

What is WCAG compliance?

Because WCAG itself is not a law, “WCAG compliance” is technically an incorrect term. Aligning with WCAG standards is referred to as WCAG conformance. WCAG is considered the global gold standard for web accessibility, and some laws cite it explicitly as a guideline for making web content accessible. Consequently, conformance with WCAG will help comply with legal mandates.

Does WCAG apply to mobile apps?

WCAG provides a comprehensive set of criteria for accessible digital content. It was originally created for websites, but adhering to WCAG success criteria is also the best-practice for all types of digital experiences, including mobile apps. Specifically, WCAG 2.1 includes criteria for tablets and mobile devices.

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