5.3.1. Enter the alt attribute to each image map and corresponding <area /> tags

Whenever an image map is included in the HTML code:

• An alt attribute must be added to the <img /> tag, as well as to each <area /> tag.
• The alt attribute of the <img /> tag must state the purpose of the image map.
• The alt attribute of each <area /> tag must state the purpose of the link.

For example, imagine a map of the United States in which you can click on each state to obtain more information about the state:

<img src="images/us-map.png" alt="Map of the United States" usemap="#us-map" />
 
<map name="us-map">
    <area shape="poly" coords="[…]" href="alabama.html" alt="Alabama (AL)" />
    <area shape="poly" coords="[…]" href="alaska.html" alt="Alaska (AK)" />
    <area shape="poly" coords="[…]" href="arizona.html" alt="Arizona (AZ)" />
    […]
</map>