Conformance Levels
WCAG has three levels of conformance: A, AA, and AAA
Level A
Minimum level of conformance. Essential accessibility features.
- Text alternatives for images
- Keyboard accessibility
- No keyboard traps
Level AA
Recommended level for most websites. Required by many regulations.
- Color contrast ratio 4.5:1
- Resize text up to 200%
- Skip navigation links
Level AAA
Highest level of conformance. Enhanced accessibility.
- Color contrast ratio 7:1
- Sign language for videos
- Extended audio descriptions
The POUR Principles
WCAG is organized around four principles: Perceivable, Operable, Understandable, and Robust
Perceivable
Information and user interface components must be presentable to users in ways they can perceive.
Provide text alternatives for non-text content
Provide alternatives for time-based media
Create content that can be presented in different ways
Make it easier for users to see and hear content
Operable
User interface components and navigation must be operable.
Make all functionality available from a keyboard
Provide users enough time to read and use content
Do not design content in a way that causes seizures
Provide ways to help users navigate and find content
Make it easier to operate through various inputs
Understandable
Information and the operation of user interface must be understandable.
Make text content readable and understandable
Make web pages appear and operate in predictable ways
Help users avoid and correct mistakes
Robust
Content must be robust enough to be interpreted by a wide variety of user agents.
Maximize compatibility with user agents and assistive technologies