Principle 2 Operable · Guideline 2.3: Seizures and Physical Reactions
2.3.1 Three Flashes or Below Threshold
Nothing may flash more than three times per second.
What this means in practice
Rapid luminance changes can trigger seizures. Applies to video, animation and ad banners. When in doubt, do not flash.
Normative wording
The binding text lives at the W3C. What you read here is our own faithful rendering – not a quotation.