In Web page development, an image map is a graphic image defined so that a user can click on different areas of the image and be linked to different destinations. You make an image map by defining each of the sensitive areas in terms of their x and y coordinates (that is, a certain horizontal distance and a certain vertical distance from the left-hand corner of the image). With each set of coordinates, you specify a Uniform Resource Locator or Web address that will be linked to when the user clicks on that area.
The X and Y coordinates are expressed in pixel s either in a separate file called a map file or in the same HTML file that contains the link to the image map. Popular tools like MapEdit provide a graphical interface for creating an image map (so that you don't have to figure out the X and Y coordinate numbers yourself).
Originally, the map file had to be sent to the server. Now the creator can place the map information either at the server or at the client (a "client-side map").
Image maps are used widely on many Web sites as a more adventuresome form of main menu.