The Web Content Accessibility Guidelines (WCAG)

The WCAG has gone through several updates since the publication of 1.0 in 1995. WCAG 1.0 has since been superseded by WCAG 2.0 and its subsequent versions.
 

• WCAG 2.0 - published 11 December 2008.
• WCAG 2.1 - published on 5 June 2018 and is now the W3C recommended version.
• WCAG 2.2 - published on October 5th 2023.

The introduction of the new iterations adds new requirements.
 

• WCAG 2.0 had 61 success criteria.
• WCAG 2.1 introduced 17 more success criteria to address mobile accessibility, people with low vision, and people with cognitive and learning disabilities.
• WCAG 2.2 expands on 2.1 with nine new success criteria, plus an update to one, with the goal of making content more accessible to a wider range of users.

The newer versions of WCAG 2 are backward compatible, meaning that all requirements in 2.0 are included in 2.1 and 2.2. So all content that conforms with the latest version of the guidelines should conform with the older versions too.

The current standing WCAG versions 2.0 and 2.1 are categorized according to four principles, perceivable, operable, understandable, and robust (POUR).

Perceivable
Elements that convey information, or website user interface components must be presented in a way that users are able to find, process, and understand.

Operable
All functionality and navigation on the website should be usable.

Understandable
Information and the operation of the user interface must be clear and understandable to users of all abilities.

Robust
The website should be capable of adapting and developing itself to support a variety of current and potential future user agents, including assistive technologies.

Under each principle are testable success criteria that provide recommendations on how to make digital content more accessible. The success criteria are classified by three levels — A, AA, and AAA — with A being the most basic level of WCAG compliance, and AAA being the strictest.

Learn more about the elements of WCAG and how to comply with its success criteria.

On 21 January 2021, the WAI released the first working draft of the WCAG 3.0. WCAG 3.0 is planned to be a major revision with the intention to make the guidelines more user-friendly than the WCAG 2 iterations, and more flexible, covering even more content, apps, and tools, as well as organizations and disabilities. WCAG 3.0 is still in development and is not expected to be finalized for the next few years.

The WCAG categorizes its conformance based on three levels: A, AA, and AAA. To be WCAG compliant, it is a requirement that one of these WCAG levels should be fully met.

Level A is the minimum level of conformance with criteria involving basic requirements that do not really impact the design or structure of the website.

Examples of Level A success criteria:
 

• All non-text content like audio or video must have a text alternative, like alt text or captions, that serves the equivalent purpose.
• Users can navigate the website effectively using only a keyboard
• If there is audio that auto-plays on your website for more than three seconds, ensure that you provide means of adjusting the volume, stopping, or pausing it.
• Offer an alternative (such as an audio track) for time-based media or video content.

Level AA is usually the level of compliance that is referred to by most accessibility laws that have adopted the WCAG. Level AA requires more commitment and technical intervention but results in a well-functioning, accessible site.

Examples of Level AA success criteria:
 

• Provide descriptive headings and labels in content.
• Navigational elements on the site, like menus, should be in a consistent, repeated position across the website.
• When executing an action on the site, like filling in forms or clicking on buttons, errors can occur on the user’s part. If an error should occur, suggestions for correction should be provided.

Level AAA is the level for optimal conformance, but because of the more stringent and detailed technical requirements, many sites aren’t at this level.

Examples of Level AAA success criteria:
 

• The visual presentation of text, and images of text, must have a contrast ratio of at least 7:1.
• Remove timing limitations from all content, unless it is for non-interactive synchronized media and real-time events.
• When a user has to submit information on a webpage, the submissions must be reversible, checked for input errors (and offer suggestions for correction if errors do occur), and a confirmation mechanism is in place to allow the user to review the submission and edit if needed.
• Images of text should be avoided or only used for decoration.

Examples of Level A success criteria:
 

• Captions should be provided for pre-recorded audio content, except when the audio is a text alternative and is labeled as such.
• When the sequence of content is essential to its meaning (such as content that spans several columns on a page), the reading sequence must be programmatically defined.
• Color must not be the only visual means of conveying information or prompting an action (such as green buttons with no text that indicates they should be selected as a ‘yes’ response).
• If a keyboard interface allows a user to move to a component of a page, that component must also allow the user to move away from it using only a keyboard interface, or the page must provide instructions for moving the focus away.

Examples of Level AA success criteria:
 

• Content display is not restricted to portrait or landscape orientation, unless a specific display orientation is essential.
• Text on a webpage (except for captions, and images of text) can be resized up to 200% without assistive technology and without loss of content or functionality.
• Headings and labels describe topics or purpose.
• Navigational elements repeated across or within a set of web pages occur in the same relative order, unless the user initiates a change.

Examples of Level AAA success criteria:
 

• All pre-recorded audio content has sign language interpretation.
• Users can suppress or postpone interruptions, except for emergency interruptions.
• A mechanism is available for identifying the meaning of or expanded form of abbreviations.
• A mechanism is available for identifying the meaning of idioms, jargon, and words or phrases used in an unusual way.

The WCAG was intended as a guideline for:
 

• Web content developers (page authors, site designers, etc.)
• Web authoring tool developers
• Web accessibility evaluation tool developers

However, as the need for website accessibility grows, it is evident that anyone who has an online presence should use it as a standard for web accessibility. This includes policymakers, managers, researchers, educators, marketers, and communicators. Also, most international legislation references WCAG 2.0 level AA as the minimum web accessibility compliance, so many countries around the world have made it a requirement for anyone who owns a website to comply with these guidelines.