You are typing a web address in the address bar of Firefox, going about your business and not bothering anyone, when suddenly an unsightly list of web addresses and convoluted website descriptions stomps into view below the address bar, assaulting your finely tuned aesthetic sensibilities. That list is an "autocomplete" feature comprised of sites you have visited, bookmarks you have created or both. You can click any item in that list to jump straight to its associated website--or you can turn around and stop those bookmarks from appearing altogether with a few clicks of a mouse.
Open Firefox and click "Tools."
Click the "Privacy" tab.
Click the drop-down menu under "Location Bar."
Click "History" or "Nothing."