What Is WCAG?

WCAG comes up as soon as digital accessibility is mentioned, often as a requirement in a specification or a contract. But what it actually is often remains unclear. In short, it’s the standard that describes how the web and apps are made usable for everyone, regardless of ability. Here’s what the term means.

A standard for digital accessibility

WCAG, Web Content Accessibility Guidelines, is an international standard with guidelines for how digital content should be designed to be usable, including for people with disabilities. It’s developed and maintained by the body that governs the web’s technical standards, and is updated in versions over time.

The point of a common standard is that it makes accessibility measurable and possible to specify as a requirement. Instead of loose ambitions about “everyone should be able to use the service,” there are concrete criteria to build toward and test against. That’s why WCAG keeps coming up in contracts and procurements: it gives a shared language for what accessibility actually means.

The standard is aimed at everyone who creates digital content – websites, apps, documents – and covers everything from how text is presented to how interaction should work for those using assistive tools.

The four principles

The entire standard rests on four core principles. Every individual requirement in WCAG belongs under one of them, which makes them a good map of what accessibility is about.

• Perceivable. The information must be possible to take in with the senses you have – what can’t be seen must be possible to hear or read some other way.
• Operable. The interface must be possible to control in different ways, for example with keyboard alone for those who can’t use a mouse.
• Understandable. Both content and function must be understandable – the text readable and the interface predictable.
• Robust. The content must work together with different tools and assistive technologies, like screen readers, now and in the future.

Together, the principles cover the entire chain: perceiving, controlling, understanding and being able to use the service with your own tools. If any one of them fails, accessibility fails, no matter how good the other three are.

The A, AA and AAA levels

WCAG divides its requirements into three levels, and the difference between them is the ambition level. It’s easy to confuse them, but in practice only one of them is the common benchmark.

Level A is basic – necessary, but far from sufficient on its own. Level AA is the practical standard and the level legal requirements normally point to. Level AAA is the strictest and rarely realistic to fully achieve for an entire service.

In almost every context, it’s level AA that applies. When someone says a website or app should be “accessible,” they mean in practice WCAG at level AA. A is too low to rely on, AAA is rarely possible to reach everywhere. AA is therefore what you normally aim for.

Three concrete examples of requirements

The standard becomes less abstract once you see what it requires in practice. Three examples among many:

Color contrast. There must be sufficient contrast between text and background, so the text can be read even by those with reduced vision. Light gray text on a white background often fails this requirement.

Keyboard navigation. Everything must be usable with keyboard alone. Someone who can’t use a mouse must be able to reach every link, button and field and do the same things as everyone else.

Alt text. Images must have alternative text that describes their content, so a screen reader can convey what the image shows to someone who can’t see it. An image without alt text is invisible to that user.

These three are just a sample, but they capture the spirit of WCAG: that nothing should needlessly shut anyone out. If you want help building or specifying accessibility requirements, it’s part of our services – get in touch and we’ll sort out what applies to you.