If you care about your personal privacy, not just online but in real life, and care about social profiling; make sure you are not logged into Facebook - and once you visit it, empty your browser's entire cache.
Or, use one browser for Facebook and use a different one for all other activity. Your best and easiest way? Use "privacy" or "incognito" browser sessions when using Facebook, then turn it off when your done.
Click here to see ---> How Facebook Is Tracking Your Internet Activity
Bottom line, this stuff isn't new, but the popularity of Facebook and the number of trackers they use in just about every website you go to is... staggering.
You've been warned.