In a report released by the Wall Street Journal it has been revealed that users are only required to log into their Facebook account once per month in order to be tracked, while the same thing goes for Twitter tracking via Tweet buttons.
That “once a month” login requirement stands even if a browser is closed or the users computer is turned off and then back on, simply leave your Facebook or Twitter accounts logged in and the tracking will continue.
While both Twitter and Facebook insist they are not attempting to use user data for nefarious purposes they do hold onto tracking information for a short period. According to Twitter their tracking data is removed “quickly” while Facebook keeps your browsing data for 90 days.
Personally I can care less if I’m being tracked, however for users who wish to remain anonymous I would suggest using a different browser to surf the web than you use for Facebook use. For example you could use Google Chrome for Facebook access and Firefox for internet browsing with the TOR plugin to keep your anonymity. You can also simply log out of your social network accounts after each use, although the TOR option above will guarantee your full privacy.