Accessibility and Usability
Web developers should strive to build web sites that are both accessible, and usable. These are different, but related concepts. Accessibility deals with whether or not people can physically access the content of a web site. Usability considers how people use the web site once they access it.
The following resources provide information about how to build accessible web sites.
Usability is concerned with designing web sites that are easy to use, and meet the needs of the site owners and visitors. It deals with wording of menus, navigation features, effectiveness of search engines, user interaction, etc.
The following links provide more information on building usable web sites.