Users differ in their ability to perceive color, and color alone should not be the sole method used to communicate meaning. Where possible, a black and white version should also be available or a caption describing pertinent information.
Success Criteria 1.4.1
Additional Resources:
Universtiy of Washington, Effective Use of Color
WebAIM Color Contrast Checker (can be used to evaluate AA and AAA pass/fail ratios on foreground/background color combinations)
Color is not used as the sole method for conveying information, indicating an action, prompting a response or distinguishing a visual element. This rule is commonly broken by marked text in red to indicate something is due. A solution is to mark the item in bold
Text and images of text have a contrast ratio of 4:5:1
Text can be resized up to 200% without loss of content or functionality
Text is used to convey inforamtion rather than images of text unless the image of text can be visually customized to the user’s requirements
Text has a contrast ratio with the background of 7:1
No images of text are used
Blocks of text can be customized by the user including foreground/background, the width is no more than 80 characters, text is not justified, line spacing (leading) is set to a space and a half within paragraphs, and paragraph spacing is at least 1.5 times larger than the line spacing, text can be resized up to 200% without users needing to scroll horizontally to read the line of text