Tagging Firefox bookmarks is the process of assigning labels and categories to them in a way that improves organization and allows them to be easily located, either from the address bar (Location bar), or from the Library.
To quickly create and tag a bookmark, use the keyboard shortcut Ctrl+D, create the bookmark, and fill in the Tags: field. In the example below, the Android Market (Google Play) was tagged SmartPhone. A bookmark can also be created, or a tag added to an existing bookmark by clicking on the star (found in the Location bar).
Tags already on your list can also be added to a bookmark by clicking the arrow to the right of the Tags: field and checking one (or more) from the list.
Or, the tags can be added or edited in the Library (keyboard shortcut Ctrl+Shift+B). Here, previously tagged bookmarks can also be accessed from the Tags menu (left side below).
To easily find a tagged group of bookmarks, type the tag name in the Location bar, and any that have been assigned that label will appear on the list.
Tags can also be added (or edited) by right-clicking a bookmark and selecting Properties from the menu.
For more general information about Firefox, and specific information about setting up and organizing bookmarks, click here.