window.history object, which is necessary for back links:
Generally speaking a back link isn't necessary� the Back button usually suffices quite nicely, and usually you can also simply link to the previous page in your site. However, sometimes you might want to provide a link back to one of several "previous" pages, and that's where a back link comes in handy.
The following pages shows you how to implement a simple, flexible back link script without many of the problems inherent in this type of scripting. We'll begin with the
basic technique, then move on to ways to customize your backlink.