How to measure the accessibility of a web project? What is important, so people using assistive technology can use a web page? And what not to do?
To answer these questions the World Wide Web Consortium (W3C) started a working group, the Web Accessibility Initiative (WAI). And this working group developed guidelines, the Web Content Accessibility Guidelines (WCAG).
In 2021, the latest version is WCAG 2.1 and version 2.2 is in development.
The four principles of WCAG
WCAG is divided into 4 principles:
- Perceivable: Information and user interface components must be presentable to users in ways they can perceive.
- Operable: User interface components and navigation must be operable.
- Understandable: Information and the operation of the user interface must be understandable.
- Robust: Content must be robust enough that it can be interpreted by a wide variety of user agents, including assistive technologies.
Each principle consists of a few guidelines. For example the principle Perceivable has the guideline Text Alternatives. All non text content should have a text alternative. Think of meaningful alternative text with images.
And to be able to test, each guideline has one or more success criteria. For example, the guideline Text Alternatives has the success criterion: All non-text content that is presented to the user has a text alternative that serves the equivalent purpose.
So, in order to deliver accessible work, you should meet the success criteria in order to comply with the guidelines that go with a specific principle.
The level of accessibility
When you start a web project, determine the level of accessibility you want to meet. There are 3 levels:
- A, for basic accessibility, that contains 25 success criteria
- AA, the global standard, that adds 13 more success criteria to A
- AAA, for dedicated projects, that adds 23 more to AA
In the legislation for government websites, most countries worldwide use WCAG AA. In 2021 in the EU version 2.1 is required. In the US version 2.0. The WAI published an overview of Web Accessibility Laws & Policies.
In order to comply with legislation, in Europe you should work according to WCAG 2.1 AA and in the US to WCAG 2.0 AA.