Not all users have a 256-colour monitor which will display colours to a reasonable degree of accuracy. Equally, they're often used for decoration. It's not obvious to blind users which is which. Colour can also affect readability for partially-sighted users. Not all colours can be rendered accurately by all browsers or all monitors.
Solutions minimise the use of red and green.
Ensure that colour-blind users can read your pages by testing them on a black and white monitor. If the contrast isn't high enough the colours need to be changed. Sound Problems People who are hearing-impaired, who do not have a sound card in their machine or who work in a noisy environment cannot hear sound clips. People will also not be able to access sound clips if they don't have the necessary software or are using a text-only browser. Solution put a link to a page with a transcript of the speech or description of the file Video Problems Video files are inaccessible to the blind, those without the appropriate software and those using text-only browsers.