Section 508 Web Standards
(f) Client-side image maps shall be provided instead of server-side image maps except where the regions cannot be defined with an available geometric shape.
What does it mean?
Client-side image maps are preferred unless there are limitations with creating links (hot spots) and it is not possible to define a region with a specific geometric shape. When the person clicks the mouse in the client-side image map, the browser decides where in the person actually clicked. The image map uses images as hot spots. People with visual disabilities do not know where the links are so each hot spot will have text equivalents that provide the necessary information about the links.
How to evaluate
All hot spots and images on the client-side image map are represented with text descriptions that provide essential information on the link and screen readers can find them. An assistive technology device such as a screen reader can find all of the hot spots. Locate server-side image maps and check to see if they can be changed to client-side image maps.
For more information
Design Resources