The WCAG Framework
WCAG organises accessibility criteria into four principles and three conformance levels — giving designers and developers a testable, shared standard to work from.
The Web Content Accessibility Guidelines give accessibility a common language. Without them, “accessible” means something different to every team on every project.
What WCAG is
WCAG — published by the W3C — is a set of testable criteria organised under the four POUR principles: Perceivable, Operable, Understandable, Robust. Each criterion has a conformance level: A is the minimum, AA is the legal and industry standard in most jurisdictions, and AAA is the highest achievable level. Most teams target AA, which covers the criteria that have the most impact for the most users.
How it is structured
Each criterion is written as a testable statement — something you can either pass or fail. “Text has a contrast ratio of at least 4.5:1” is a WCAG AA criterion. “Links have visible focus indicators” is another. This structure means accessibility can be audited, tracked, and integrated into design and development processes rather than treated as a matter of opinion.
What it does not cover
WCAG defines the floor, not the ceiling. Meeting AA conformance means your interface clears the minimum bar — it does not mean it is easy to use, well-structured, or genuinely inclusive. Usability for people with cognitive disabilities, for example, is addressed only partially by WCAG. Meeting the standard is necessary but not sufficient.
The versions
WCAG 2.1 added criteria for mobile accessibility and cognitive impairments over WCAG 2.0. WCAG 2.2 added further focus-related and touch criteria. Most audit tools and legal frameworks reference 2.1 AA as the current baseline. WCAG 3.0 is in development and will change how scoring works, but 2.x remains the operative standard.
The takeaway
Learn WCAG 2.1 AA as your working standard. Treat each criterion as a design specification, not a compliance checkbox. The specific criteria for colour contrast, keyboard navigation, and focus management are where most interfaces fail — and where the biggest gains are made.