UX glossary
WCAG
WCAG (Web Content Accessibility Guidelines) are the W3C’s internationally recognized guidelines for accessible web content. They define testable criteria that laws around the world build on.
Imagine a team gets a clear order: “Our website has to be accessible.” Questions pop up right away. Is good contrast enough? And how do you know when you’re done?
That’s exactly what WCAG is for. It turns the big idea of accessibility into a list of concrete, testable requirements.
Explained simply
WCAG stands for Web Content Accessibility Guidelines. They’re published by the World Wide Web Consortium (W3C), the body that also maintains standards like HTML and CSS. The first version of WCAG 2 came out in 2008. The current version, WCAG 2.2, was published in October 2023 and updated again in December 2024.
Think of WCAG as a building code for websites. A building code doesn’t tell you what a house should look like, but it does set how wide doors and how high steps may be. WCAG leaves you the same creative freedom but sets minimum standards.
Four principles, three levels
WCAG is organized around four principles. Content has to be perceivable (for example, alt text for images), operable (fully usable with a keyboard, say), understandable (clear language, predictable behavior) and robust, meaning it works reliably with browsers and assistive tools like a screen reader.
Below these principles sit 13 guidelines, and below those the actual success criteria. Each criterion belongs to a conformance level: A is the minimum, AA the usual target, and AAA the highest level. One AA example is a contrast ratio of at least 4.5:1 for regular text. The versions build on each other: according to the W3C, content that meets WCAG 2.2 also meets WCAG 2.1 and 2.0.
Which version applies legally?
Laws usually don’t point to WCAG directly but to the European standard EN 301 549. Its version V3.2.1, the reference so far, requires the level A and AA criteria from WCAG 2.1 for websites. In Germany, it’s the benchmark both for public bodies under the BITV 2.0 (the federal accessibility regulation for government IT) and for companies covered by the BFSG, Germany’s implementation of the European Accessibility Act.
In September 2026, the new version V4.1.1 of EN 301 549 was published, aligned with WCAG 2.2 AA. It may take a while until it’s listed in the Official Journal of the EU and carries full legal weight. In practice: if you’re building something new today, aim straight for WCAG 2.2 AA. For more on the legal side, read The BFSG in Practice: What Germany’s Accessibility Act Means for Websites and Apps.
An example
Here’s an example: an online shop marks required fields in its checkout with nothing but a red border. An audit flags several problems at once. Color is the only signal (criterion 1.4.1), there’s no label a screen reader can announce (3.3.2), and the error message doesn’t say what’s wrong (3.3.1).
After the fix, required fields say “required” in their label, and error messages explain the problem in words, such as “Please enter a five-digit ZIP code.” Instead of a vague complaint, the team now has a clear to-do list it can work through and test again.
Common misconceptions
Automated testing tools only cover part of the criteria. Whether alt text makes sense is something a person has to judge. WCAG isn’t just for websites, either: EN 301 549 applies it to apps and documents as well. And its successor, WCAG 3, is still an early draft, so there’s no reason to wait for it.
In practice
- Use the quick reference. The official WCAG 2.2 Quick Reference can be filtered by level and topic and explains every criterion with techniques.
- Combine tools with manual checks. Automated tests quickly catch missing alt text and contrast issues, but keyboard and screen reader testing is still manual work. Learn how in Accessibility Testing: Tools and Methods for UX Designers.
- Build the criteria into your design system. Once buttons, form fields and colors are WCAG-compliant, every new page inherits that quality.
Related terms
Accessibility, Screen Reader, Design System