WCAG (Web Content Accessibility Guidelines) is the international standard for making websites usable by people with disabilities. Published by the W3C, it is a list of specific, testable requirements, such as text contrast, keyboard access and captions, and it is the benchmark most accessibility laws and audits refer to.
How WCAG is structured
WCAG is organised around four principles, often shortened to POUR: content must be Perceivable, Operable, Understandable and Robust. Under these sit guidelines, and under those sit success criteria, which are the actual pass or fail checks.
Each success criterion has a level. A is the minimum, AA is the level most laws and contracts ask for, and AAA is the strictest and is not expected for whole sites. The current version is WCAG 2.2, published in October 2023; it is backward compatible, so meeting 2.2 also meets 2.1 and 2.0.
What some AA checks look like in practice
- Normal text needs a contrast ratio of at least 4.5:1 against its background; large text needs 3:1.
- Every function must work with a keyboard alone, and focus must be visible.
- Images that carry meaning need a text alternative such as alt text.
- Form fields need labels, and errors must be described in text, not just shown in red.
- Pre-recorded video with sound needs captions.
- New in 2.2: interactive targets should be at least 24 by 24 CSS pixels or have enough space around them.
A worked example: auditing a salon site
A salon runs a free automated checker and gets three warnings. A manual pass finds more: pale pink button text on a white background fails contrast, the booking widget cannot be operated with the Tab key, the gallery images have no alt text, and the "required" fields are marked only by colour. Fixing these takes a darker button colour from the brand palette, a keyboard-friendly booking tool, short image descriptions and a written "required" label. Automated tools catch only a portion of WCAG issues, which is why the manual pass mattered.
When WCAG matters for a small business
Legal requirements depend on where you operate and who your customers are. In the US, ADA lawsuits over inaccessible websites are common and WCAG AA is the usual yardstick. In the EU, the European Accessibility Act applies to many consumer-facing services from June 2025, with exemptions for some microenterprises. If you are unsure, aim for AA anyway: it also makes the site easier for everyone on a small phone screen.
WCAG mistakes
- Relying on an overlay widget. A toolbar script does not fix inaccessible underlying code.
- Trusting automated scores alone. Keyboard and screen reader checks need a human.
- Checking only the homepage. Forms, checkout and booking pages are where failures hurt most.
- Treating it as one-off. Every new page or plugin can introduce new failures.
Related terms
- Web accessibility: the goal WCAG turns into measurable rules.
- ARIA: attributes that help custom widgets pass WCAG checks.
- Screen reader: one of the main tools used to test conformance.
- Alt text: covers one of the most frequently failed criteria.