This post is about Facebook Disconnect, a Google Chrome extension.
A lot of third-party websites, in other words, Non-Facebook sites use Facebook Connect... etc to let users share stuff on Facebook. Well, this means every time a user visits any of these sites, Facebook may be notified. So your surfing habits are probably tracked.
If this concerns you, Facebook Disconnect is the thing for you. It works by blocking third-party sites from notifying Facebook about your visit. You can, however, access Facebook directly.