Most of the common WWW client programs keep track of pages that you have viewed and allow you to bring back a previous page. This mechanism is activated in different ways depending on the type of client.
If you use Netscape, then backtracking is very easy. Just hit the button marked "Back" at the top of the window, it will bring you back to the previous page. To bring up the list of pages you have visited, press the "Go" menu, then select the page that you want to jump back to. The "Forward" button will bring you to the page next to the current page in your viewing history.
Now, hit the "Back" button to see what happens.