WCAG Levels
POUR Principles
The four pillars organizing all WCAG criteria: Perceivable (can users sense it?), Operable (can they interact?), Understandable (can they comprehend?), Robust (does it work with assistive tech?). If any pillar fails, the content is inaccessible.
In plain terms
The four big ideas behind every rule: can people Perceive it, Operate it, Understand it — and will it work with their assistive tech (Robust)?
Why this matters
POUR is the mental model that makes all 80-plus criteria comprehensible. Understanding the four questions behind them lets you reason about accessibility instead of just ticking boxes.