This translation has not been editorially reviewed yet. The German version is authoritative. Deutsche Fassung →
Flashing content: the limit of three times per second
No content may flash more than three times per second. This criterion protects people with photosensitive epilepsy, and it's the only one where a violation can be immediately harmful to health.
- In practice, violations are rare, but serious when they happen: fast video cuts, ad banners with a flashing effect, loading animations with a hard light-dark change.
- Because an automated test can only judge moving content to a limited extent, this criterion is a case for human review — especially for embedded videos that come from a third-party platform.
FAQ
Does this also apply to embedded videos from third parties?
Yes. Whoever embeds the content on their page is responsible. A third-party video with a flashing sequence becomes content on your page through the embed.
How do I spot problematic spots?
Watch for fast light-dark changes over large areas, especially with a red component. There are analysis tools for video material; for individual effects on the page, a human review helps.