Principles of Accessible Design

Some principles (in all three WAI Guidelines) that promote independence and redundancy:

Provide alternative content
Text may be rendered graphically, as speech, as Braille.
Meets low bandwidth needs.
Follow specifications
Valid documents benefit assistive technologies, transformations (e.g., mobile gateway).
Built-in accessibility features, reliability, interoperability.
Use style sheets
Encode information in markup, metadata (help machines understand).
Style as a separate complement to structure allows easier management, diversity of presentation.
Cascade allows users to override styles when necessary.