Since forms are the beginning and end of many sites’ business objectives, it’s important to consider the likelihood that a significant proportion of your visitors cope with reduced physical or mental function that complicates their efforts to use the Web. Impairments relevant to the design of websites can be grouped into several basic categories, each illustrated with common examples:
If users’ range of motion is limited, so is their ability to use a mouse, keyboard, or perhaps both.
Broken arms and/or fingers
Chronic tendinitis or repetitive strain injury
Paraplegia and quadriplegia
The user interface design of personal computers and mobile devices is largely predicated on users’ ability to respond using their senses of sight, hearing, and touch. Of these, eyesight is most significant to the design of websites, particularly those that rely on forms to meet their business objectives. If users can’t see a form or the data they’re putting into it, their ability to use such sites is greatly reduced.
Age-related degeneration of visual acuity
Di- and monochromaticity (color blindness)
The perception of value in media content, including web content, is entirely a function of the brain and mind. A user who can’t concentrate on a site or quickly comprehend its value is unlikely to stick around—thus the emphasis on brevity.