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Flickering content

Avoid causing the screen to flicker with a frequency greater than 2 Hz and lower than 55 Hz.

Unacceptable levels of screen flicker can trigger seizures in users with photosensitive epilepsy. Many other users find it annoying. Flashing or flickering elements are usually added through technologies such as animated gif's, Java applets, or third-party plug-ins or applications.

In general, avoid animation unless you have a compelling reason to use it. Do not use scrolling text, which is inaccessible to screen readers and impossible for some people to read.

The following link demonstrates unacceptable screen flicker. Do not follow this link if you have photosensitive epilepsy:
http://ncam.wgbh.org/richmedia/media/flicker_demo.html

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