3.2.1 On Focus
Conformance level: A
Criterion released in WCAG version: 2.0
TL;DR: Don’t trigger unexpected changes just because something receives focus. Keep focus behaviour predictable; require an explicit user action for major changes.
Official description of the success criterion
When any user interface component receives focus, it does not initiate a change of context.
What to do?
Ensure elements do not initiate a change of context when they receive focus.
Why is it important?
Prevents unexpected changes that can confuse users.
Common pitfalls
Opening context-changing elements when the component receives focus. Example: opening a new window.