1.4.1 Use of Color: Color is not used as the only visual means of conveying information, indicating an action, prompting a response, or distinguishing a visual element. (Level A)
Note: This success criterion addresses color perception specifically. Other forms of perception are covered in Guideline 1.3 including programmatic access to color and other visual presentation coding.
This success criterion requires that color should not be the sole method of conveying information to the users. People with low vision, color blind, elderly & people with situational disabilities depend on more than one way to find information on the page & if that information is represented in the form of color alone, then it fails this check point.
Some of the best examples of use of color are, marking input fields in red color to convey errors or ‘required’ information, a button marked in green that performs the essential action like submitting a form, a text prompt that says “click the green button to submit the form”, a graph that uses only color to indicate the growth/decline percentage, etc. In all the above examples user is being asked to refer to a particular color to find information & if they cannot get to that color or understand what that color represents, then it is a failure of this check point.