The image that is going to form the map is inserted into the page using the <img /> element as normal, except that it carries an extra attribute called usemap. The value of the usemap attribute is the value of the name attribute on the <map> element, which you are about to meet, preceded by a pound or hash sign.
The <map> element actually creates the map for the image and usually follows directly after the <img /> element. It acts as a container for the <area /> elements that actually define the clickable hotspots. The <map> element carries only one attribute, the name attribute, which is the name that identifies the map. This is how the <img /> element knows which <map> element to use.
The <area> element specifies the shape and the coordinates that define the boundaries of each clickable hotspot.
You can feel the map concept by placing the mouse cursor on the image object.