Firefox saves a lot of different information, but when it comes to cleaning your browser history up – how do you know what to keep and what to save? I figured I would take a minute or two to go through each thing that is saved in your Firefox history so you’ll know what exactly you are saving.
Browsing & Download History: Browsing history is the list of sites you’ve visited that are shown in the History menu, the Library window’s History list, and the Location bar autocomplete’s address list. Download history is the list of files you’ve downloaded that are shown in the Downloads window.
Form & Search Bar History: Form history includes the items you’ve entered into web page forms for Form autocomplete. Search Bar history includes items you’ve entered into Firefox’s Search bar.
Cookies: Cookies store information about websites you visit, such as site preferences or login status. This includes information and site preferences stored by plugins such as Adobe Flash. Cookies can also be used by third parties to track you across sites.
Cache: The cache stores temporary files, such as web pages and other online media, that Firefox downloaded from the Internet to speed up loading of pages and sites you’ve already seen.
Active Logins: If you have logged in to a website that uses HTTP authentication since you most recently opened Firefox, that site is considered “active”. Clearing this logs you out of those sites.
Offline Website Data: If you’ve allowed it, a website can store files on your computer so that you can continue to use it when you are not connected to the Internet.
Site Preferences: Site-specific preferences, including the saved zoom level for sites, character encoding, and the permissions for sites (like pop-up blocker exceptions) described in the Page Info window.
That should cover all the basics – hope that helps to make sense out of what Firefox saves as far as your history goes.