Web accessibility is designing websites that provide enjoyable, efficient, learnable, predictable and memorable user experience for users who have some form of disability.

These include:

• Users who cannot see, hear, move, or able to process some types of information easily.
• Users that have difficulty reading or understanding text.
• Users who may not be able to use a keyboard or mouse.
• Users with text-only screen, a small screen or slow internet connection.
• Users who have earlier versions of a browser or different operating system.

(Publication Source: Interaction Design, by Sharp, Rogers, Preece, pg. 256)

In general, it is respectful to make Web content more usable and understandable to all audiences.