Forms of disability
Vision impairments
Colour blindness affects between 8% and 10% of the male population in the UK. If there is not enough contrast between foreground and background colours on your web site (for example, with your text), none of them would be able to read what is your site says.
Small text sizes limit people with restricted vision. Most Internet browser software allows visitors to resize the text that appears on web pages to make it more readable. However, many web sites have this feature turned off.
If your web site provides prompts and navigation tools such as menu systems in visual format only and without alternative text, it will cause problems for a blind person using screen reader software. There are many other things to consider, if your web site is to be used effectively by blind people. The software that they use relies on web sites being built in line with best practice.
Mobility impairments
People with mobility impairments may lack the dexterity or hand-eye co-ordination to use a mouse, and may have to rely on the keyboard or another device to help them. With this in mind, web site navigation systems should be easy to use and identify. A simple test is to check whether you can fully access your own web site without a mouse, using only the tab key on your keyboard or access keys (where the keys on your keyboard are assigned special actions).
Cognitive (learning) impairments
People with cognitive or learning impairments such as dyslexia or attention deficit disorder need a logical order for content, well presented text written in clear sentences and graphical icons to aid navigation.
For example, users with dyslexia would find it difficult to read a page with unbroken text stretching across the screen. As the eyes scan across, it is very difficult to read and the point of vision gets lost. Unjustified text (not aligned at the right hand side) is much easier to read than justified (aligned) text. Further information is available at Designing web pages for dyslexic readers.
Hearing impairments
Audio and video content is used increasingly on the Internet, so it is important to include text transcripts of any file that would otherwise rely on sound. People with hearing impairments will then be able to follow the action.
