If you really get absorbed in following links here, this whole set of pages might take a couple of hours to work through systematically. Sometimes you keep clicking on things and getting interested and lose track of where you are. Not to worry. (1) In most Mosaic and Netscape clients, there's a history menu you can find up above (perhaps under "Navigate") that records the pages you visited on this session and lets you hop back to an earlier one by clicking on it. (2) In the worst case, virtually all WWW browsers let you go "back" -- in Lynx, e.g., you just hit cursor-left, and in Mosaic and/or Netscape there's a button at the top of the display with an arrow pointing left; if you're really lost, hit "back" a few times until you find yourself someplace familiar.