Browsers have a forward and back button. These help you navigate within your recent browser history. But, when you land on a site from an external link you sometimes want to, for example, go up the URL path to higher ‘folders’ within the site.
Example, your at http://somewhere.com/land/animals/waterbuffalo.html. How do you get to the land folder? Maybe there is something there, or how do I get to somewhere.com itself. The answer is you click on the address bar and edit the URL. Yuck! What is this, the 1800’s? Plus on any kind of smartphone this is pain to do. Plus, did you ever try to guide over the phone a non-compute savvy person to navigate on a site by editing a URL? Even more painful.
The old Google add-ons for various browsers used to have a page up widget. On FireFox I now use “Dir Up”.