When browsing through your Firefox profile folder, you might see a lot of odd files. Some might make sense, such as your searchplugins folder, however others might seem a little odd.

Here are some of the important files you might seen in your profile folder and what they are used for.

• search.sqlite and the searchplugins folder – The first file, search.sqlite stores the order that your search engines (for the search box) are sorted. Inside of the searchplugins folder you can find all the extra search engines you have installed.
• mimeTypes.rdf – your preferences with respect to what Firefox does when it comes across known file types.
• formhistory.sqlite - this is where information that you have searched for or entered into forms on web sites (think autocomplete) is stored.
• places.sqlite – this is the file that contains your bookmarks and previously visited web sites.
• cert8.db – all your security certificate settings and any SSL certificates you have imported are stored here.
• permissions.sqlite – the file here stores site specific preferences, such as if you allow it to install add-ons, show images, display popups or any special orders you have allowed for that domain.
• key3.db and signons3.txt – these are the files that store your password information you have saved.
• persdict.dat – this file will hold your words you have personally put into Firefox’s built in spellchecker.
• cookies.sqlite – your web site cookies are stored here.

Now, I do know there are more files – however, these are the files that are most important for you to know about, just in case something bad might happen.  Hopefully, this additional documentation will come in handy when troubleshooting your own Firefox issues or problems.