By the end of this lesson you can
- Explain what WCAG is and how it is structured.
- Describe the four POUR principles and conformance levels.
- Find and read success criteria relevant to a design.
The idea
The Web Content Accessibility Guidelines (WCAG), published by the W3C, are the international standard for digital accessibility. They are referenced by laws and policies worldwide and apply to websites, apps and documents. WCAG 2.2 is the current version.
POUR
Guidelines are grouped under four principles. Content must be:
- Perceivable: people can perceive it (text alternatives, captions, contrast).
- Operable: people can use it (keyboard access, enough time, no seizure triggers, clear navigation).
- Understandable: people can understand it (readable text, predictable behaviour, help with errors).
- Robust: it works with current and future assistive technologies (valid, semantic code).
Success criteria and levels
Each guideline has testable success criteria at three levels: A (minimum), AA (the usual target in laws and policies) and AAA (enhanced). Most organisations aim for AA.
Reading WCAG
The official "Understanding" documents explain each criterion's intent, who it helps and examples. The "How to Meet WCAG" quick reference lets you filter criteria by topic and level.
Why it matters in real projects
WCAG gives teams a shared, testable definition of accessibility. Designers who can read and apply it can catch problems early, explain requirements to stakeholders and work confidently with developers and auditors. Many public sector and large private organisations require WCAG AA conformance by law or contract.
A realistic example
A product manager asks whether a new grey placeholder text style is "accessible enough". The designer looks up success criterion 1.4.3 Contrast (Minimum), Level AA, which requires 4.5:1 for normal text.
The grey measures 2.8:1, so it fails. The designer also notes that placeholders should not replace labels. The team uses a darker grey and visible labels, and the designer links the WCAG criterion in the design documentation.
Step by step
Open the quick reference
Use the W3C "How to Meet WCAG" page.
Filter to AA
Filter to levels A and AA.
Read POUR
Skim criteria under each principle.
Pick five relevant criteria
Choose ones that apply to a design you are working on.
Read the Understanding docs
Read intent and examples for each.
Check your design
Evaluate your design against them.
Common mistakes
Mistake Treating WCAG as the only goal.
Instead Meeting WCAG is the floor; test with real users too.
Mistake Not reading the intent.
Instead Read the Understanding documents for context.
Mistake Assuming AA covers everything.
Instead Consider AAA criteria where they matter for your users.
Check your understanding
Choose an answer, then check it. There is an explanation either way.
Practice exercise
Exercise · about 45 min
WCAG mapping
Map WCAG criteria to a screen.
Steps
- Choose one of your screens.
- Find ten relevant AA criteria.
- Check the screen against each.
- Record pass, fail or unsure with notes.
Deliverable
A WCAG mapping table for the screen.
Self-assessment
Tick each item when it is true of your exercise. Be honest; this is for you.
4 items
Summary
- WCAG is the international accessibility standard.
- It is organised under POUR principles.
- Success criteria have A, AA and AAA levels; AA is typical.
- Read the Understanding docs for intent.
Further reading
Third-party sources, chosen for reliability. They open in a new tab.
Your notes
Marking complete updates your course and roadmap progress.