This <map> tag is normally use to defines the images with clickable areas
with the help of <area> tag.
And here by image map which consist the image with clickable areas , can click on image and redirect to any particular destination.
Let's understand this by the following example:
<p> Example of map tag. </strong> </p>
<img src="image/himalayas.png" usemap="#manish">
<area shape="rect" coords="953,905,14,0" href="http://ittrainingclasse/">
Example of map tag.
As soon as you click on this you will be redirecting to the homepage of this website.