The Web is fundamentally designed to work for all people, whatever their hardware, software, language, location, or ability. When the Web meets this goal, it is accessible to people with a diverse range of hearing, movement, sight, and cognitive ability.
Although not all disabilities impact internet use, businesses would be unwise to purposely exclude 25, 15, or even five percent of their potential customers. In education and government, in many cases it is illegal discrimination. – WebAIM