- Digital Accessibility
- Physical Accessibility
The Web Content Accessibility Guidelines (WCAG) are the most popular digital accessibility standards.
WCAG outlines the requirements that most consultants and subject matter experts use to test for digital accessibility. It is also specified as the official requirement under certain laws, like Section 508 of the Rehabilitation Act, and it is commonly pointed to in digital accessibility lawsuits and complaints.
The World Wide Web Consortium (W3C) Web Accessibility Initiative (WAI) publishes and maintains WCAG.
The first version of WCAG was published in 1999. The latest version, WCAG 2.1, was published in 2018.
WCAG is organized by four Principles, which state that content must be Perceivable, Operable, Understandable, and Robust. The four Principles are arranged by supporting Guidelines, which are further broken into individual Success Criteria. Success Criteria act as the specific and testable accessibility requirements.
Success Criterion 1.4.1 Use of Color states: "Color is not used as the only visual means of conveying information, indicating an action, prompting a response, or distinguishing a visual element."
This Success Criterion is one of the Success Criteria under Guideline 1.4 Distinguishable, which states: "Make it easier for users to see and hear content including separating foreground from background."
This Guideline is one of the Guidelines under Principle 1. Perceivable, which states: "Information and user interface components must be presentable to users in ways they can perceive."
There are three conformance levels of WCAG: Level A, Level AA, and Level AAA.
Level AA conformance of WCAG 2.0 or 2.1 is most common.
Each Success Criterion is assigned a conformance level of A, AA, or AAA, with A as the lowest level of compliance and AAA as the highest. To qualify as meeting a certain conformance level, all content on a webpage or website must fully meet at least that level.
To achieve Level AA conformance therefore means to satisfy all Level A and AA Success Criteria. "It is 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," according to W3C's Understanding Conformance.
To claim compliance or conformance with WCAG requires understanding what constitutes conformance. W3C's Understanding Conformance explains: "Conformance to a standard means that you meet or satisfy the 'requirements' of the standard. In WCAG 2.0 the 'requirements' are the Success Criteria. To conform to WCAG 2.0, you need to satisfy the Success Criteria, that is, there is no content which violates the Success Criteria."
There are five requirements for conformance, per W3C:
For more information, review W3C's Understanding Conformance.