Bookmarks are stored in your profile folder. (See [http://support.mozilla.com/en-US/kb/Profiles Profiles | How to | Firefox Help].) In recent versions of Firefox, favorites (known in Firefox as bookmarks) are stored in a database file named places.sqlite which also stores browser history. You can't read places.sqlite without a program that understands the sqlite format. Firefox also backs up your bookmarks in a format called JSON. This is slightly easier to read. Does this help? Do you have a specific need for bookmark information in a particular format?

See also: * http://kb.mozillazine.org/Backing_up_and_restoring_bookmarks_-_Firefox * http://kb.mozillazine.org/Export_bookmarks