A server-side image-map:
The ismap attribute is a boolean attribute.
When present, it specifies that the image is part of a server-side image-map (an image-map is an image with clickable areas).
When clicking on a server-side image-map, the click coordinates are sent to the server as a URL query string.
Note: The ismap attribute is allowed only if the <img> element is a descendant of an <a> element with a valid href attribute.
In XHTML, attribute minimization is forbidden, and the ismap attribute must be defined as <img ismap="ismap" />.