Web Design in a Nutshell, 3rd Edition

There are many advantages to using client-side image maps . They are self-contained within the HTML document and do not rely on a server to function. This means you can test the image map on your local machine or make working site demos for distribution on disk. It also cuts down on the load on your server and improves response times. In addition, complete URL information displays in the status bar when the user mouses over the hotspot (server-side image maps display only coordinates).