Web Accessibility
There are several studies that estimate that 1 in 4 users (25%) have some type of visual disability. Approximately 1 in 12 men and 1 in 200 women have problems with color blindness or color perception to varying degrees.
The W3C has several initiatives aimed at raising awareness and encouraging the consideration of these visually impaired users when developing any web application or service (Web Accessibility Initiative, WAI).

