It is usually not a big issue if you stay logged in on everyone’s favorite social networking site Facebook after you have finished getting your daily dose of social love and all the good stuff that comes from it. If you are working on a multi-user PC, a public computer, or any other system where other users may access the same browser that you have used to access Facebook, then you may want to consider logging out of the social networking site to avoid that those third parties access your Facebook account. If you do not log out of Facebook in this case, those users can access almost all the information that you share on Facebook, including private messages, and photos that you have only uploaded for your boyfriend.
Logging out of Facebook when you are done using the site has another effect: If you are not logged in, you can’t be traced anymore by those cookies.
Facebook Auto-Logout is a free browser extension for the Firefox web browser that is making sure that you are logged out of Facebook after some time of inactivity, or when you close the web browser. Once you have installed the Firefox add-on, there is nothing else to do as it works automatically from that point on.
You’ll be automatically logged out of Facebook after having closed the site for at least 60 seconds in the browser, or when the browser is closed, whichever comes first. If you think that 60 seconds is too much or too little, you can change the preference in the options.
Enter about:addons in Firefox’s address bar and click on the options button next to Facebook Auto-Logout in the addons manager. Here you find the setting to change the automatic logout interval from 60 seconds to a value that you prefer instead.
You will also notice that you can enable or disable the logout notifications here. For the technical interested users: The add-on clears the cookies that Facebook uses to determine if a user is logged in on the site.