Operable
WCAG 2.3.1
Seizure Safety
Nothing on the page may flash more than three times in any one second — fast flashing can trigger seizures in people with photosensitive epilepsy. Avoid strobing animation, flashing ads, and rapid red flashes. When in doubt, don't flash.
In plain terms
Nothing should flash more than three times a second — fast flashing can trigger seizures in some people.
Why this matters
Content that flashes more than three times a second can trigger seizures in people with photosensitive epilepsy — a rare but genuinely dangerous, even life-threatening, failure.
How to detect
Quick check
Check any flashing, strobing, or rapidly-changing content (animations, ads, video, transitions). Nothing should flash more than three times in one second; when unsure, test with PEAT, the Photosensitive Epilepsy Analysis Tool.