What are the WCAG and what does level AA mean?

WCAG (Web Content Accessibility Guidelines) is the W3C technical standard defining how to make a website or web application accessible to people with visual, motor, hearing or cognitive disabilities. The current version is WCAG 2.2, published in 2023, organized around four principles known by the acronym POUR: perceivable, operable, understandable, robust. Each success criterion belongs to one of three levels, A, AA or AAA, in increasing order of strictness; level AA is the one required by European regulation and the practical reference for most corporate and institutional websites. In practice, AA conformance means text with a minimum 4.5:1 contrast ratio, full keyboard navigation, a visible focus indicator, alternative text for images and no element that relies on color alone to convey information. WCAG is not a law: it is the technical standard that laws, such as the European Accessibility Act, point to when they define what "accessible" means.

See also: European Accessibility Act (EAA) · EU directive requiring accessibility, from 2025, for consumer-facing e-commerce, banking, e-books and ticketing.

The four principles and the three levels

Perceivable means information does not depend on a single sensory channel: an informative image has alt text, a color is never the only way to flag an error. Operable is about interaction: any function reachable with a mouse must also be reachable by keyboard, with no focus traps. Understandable covers clear language and error messages that say what to fix. Robust is the most technical one: correct semantic markup, components that expose role and state to assistive technology. Level A covers the most severe barriers, the ones that shut a group of users out entirely; level AA adds the requirements that make a site decently usable, contrast and minimum touch-target size included; level AAA is stricter still (7:1 contrast) and the W3C itself advises against requiring it for a whole site, because for some content not all of its criteria can be met. In Europe the regulatory reference is EN 301 549, which in turn points to WCAG 2.1 level AA for the digital accessibility requirements demanded of the public sector and, under the Accessibility Act, of a growing share of the private sector.

An enterprise example

A company redesigning its corporate site often discovers WCAG problems during the pre-launch audit, not before: a contact form with no labels associated to its fields, a menu that opens only on mouse hover and not with Enter or Tab, a block of light-gray text on white below the required contrast ratio. Someone browsing with a mouse and unimpaired vision never sees them. Fixing them after the redesign is done costs layout changes, not just CSS: a skipped heading level often means revisiting the page structure.

How it is tested

An automated scan (axe, Lighthouse, WAVE) catches a measurable minority of real issues, typically contrast, missing markup and absent labels. It does not catch an illogical tab order or an error message nobody can act on: those need manual testing, by keyboard and with a screen reader, which the W3C WAI documents as the evaluation method.

Why it matters for decision makers

WCAG is the technical reference behind every digital accessibility obligation in Europe, so ignoring it is no longer a product choice: it is a legal exposure, now that the Accessibility Act has applied since June 28, 2025. But the reason to invest is more direct: an accessible site is more robust for everyone, carries semantic markup that also helps a search engine read the page, and is cheaper to maintain. The decision during a redesign is which level and from which phase: built in from the start costs a fraction of what it costs chased at the end.