Glossary / WCAG
WCAG
WCAG (Web Content Accessibility Guidelines) is the W3C standard for making web content usable by people with disabilities across visual, auditory, motor, speech, cognitive, language, learning, and neurological needs. It is organized around four principles—Perceivable, Operable, Understandable, and Robust (POUR)—with testable success criteria at Levels A, AA, and AAA. WCAG is a conformance standard, not a design system or an automated test suite: teams use it to set requirements, evaluate representative pages and states, and combine technical testing with human evaluation.
What to know
- Versions: WCAG 2.2 is the current Recommendation used here. It builds on 2.1 and 2.0; 2.2 adds criteria such as Focus Not Obscured, Dragging Movements, Target Size (Minimum), and Accessible Authentication. WCAG 3 is a separate developing effort, not a replacement conformance target today.
- Principles: Perceivable information and UI; Operable controls and navigation; Understandable content and behavior; Robust markup that works with current and future user agents, including assistive technology.
- Levels: A is the baseline, AA is the common product and procurement target, and AAA is a stricter set that is not generally achievable for every kind of content. A claim should name version, level, and scope (for example, WCAG 2.2 AA for specified pages).
- Success criteria: Each criterion is normative and has a conformance level. Techniques and sufficient techniques are informative examples, not the only valid implementations.
- Conformance scope: Conformance applies to complete pages and complete processes. A checkout flow cannot be made conformant by checking only its first screen; all steps, states, and supplied alternatives matter.
- Accessibility is broader: WCAG conformance does not guarantee an excellent experience, cover every disability need, or replace user research and usability work.
Engineering practice
Turn criteria into design-system requirements and testable acceptance criteria early. Test representative templates and interaction states: empty, error, loading, expanded, modal, responsive, zoomed, and authenticated. Use semantic HTML first, then ARIA only where native semantics are insufficient. Combine automated checks, keyboard-only testing, screen-reader testing, zoom/reflow checks, contrast measurement, and evaluation by people with disabilities. Record defects with criterion, reproduction steps, impact, affected flow, and a proposed fix. Avoid claiming blanket compliance from a scanner score or a single audit.
Interview questions
- What does POUR stand for? Perceivable, Operable, Understandable, Robust; the principles organize the guidelines and criteria.
- What does WCAG 2.2 AA mean? The scoped content satisfies all applicable Level A and AA success criteria in WCAG 2.2; it is not a promise that every possible user task is effortless.
- Can an automated scan prove conformance? No. Tools can find some machine-detectable failures, but cannot reliably judge meaningful alternatives, interaction quality, comprehension, or all keyboard and assistive-technology behavior.
- How do you make a product WCAG-aligned? Establish scope and target, map criteria to reusable components and acceptance checks, test full flows and states, involve users, and maintain remediation ownership.
- What is the difference between a guideline and a success criterion? Guidelines express broad goals; success criteria are the testable normative requirements used for conformance.