These help:
If the first page was navigated to a certain place by clicking an anchor, when you go to another page and hit back, it'll take you to the place where it loaded at the anchor.
For example, here on the forums, if you click the link on the main forum page to go to the last post in a thread, that's using an anchor. If you click that link to load that page, go somewhere else, and go back until you get to that thread again, the page will load at the location of the anchor you originally clicked.