Ensure that all information conveyed in color is also available without color.
- People who are colorblind may not be able to decipher the information portrayed in color.
- If the foreground and background colors or tones are similar the user may not be able to read any of the sites content.
- Don’t say, “the information presented in green shows new employees, and the information in blue shows existing employees.”
- Use context or markup to convey differences in color-coded information.
- On graphs use different textures to convey the information (dotted, dashed, solid lines) instead of just color.
To test this requirement, try printing the Web page in grayscale (without color) to see if the navigation and content can be interpreted.