I conducted a completely nonscientific, haphazard public poll at a bar one evening last week. I asked a variety of people if they thought that Facebook knew what sites they visit that aren't Facebook. The results were all over the map, with many folks laughing and saying, "Probably, right?"
I then asked them: "If it's true that Facebook is tracking your browsing habits, would that a problem for you?" Most answered yes, reflected for a second, looked a little concerned, and asked me if it were true.
[ Also on InfoWorld.com: Take a tour of Facebook's greatest missteps in the slideshow, "Facebook's biggest faceplants." | Get the latest news and insight on the tech industry from the InfoWorld Daily newsletter. ]
The answer is that yes, it's true -- but not for every site. Those of us who know how the Web works know that every time you visit a page with a Facebook, Google+, or Twitter link, the code behind that link actually comes from Facebook or Twitter servers, so if you're surfing to that page with the same browser that you're currently logged into Facebook or Twitter with, then they know you're on that site. They know how long you spent on that site, how often you visit, and so forth. It's all very simple to do. Yet most people are cheerfully oblivious to this fact.
The informed few take special precautions to eliminate or at least reduce their exposure. Several browser plug-ins can help control cookie dispensation -- and some browsers have a form of this capability built right in. The default for all of them, however, is to allow all cookies. Thus, millions of people blithely allow their Internet movements to be tracked by anyone with enough of a footprint, like Facebook, Google, and Twitter. And this information is not anonymous. It's tied to the account, which in many cases is tied directly to your identity. If someone at any of these companies wants to find out what you -- specifically you, not simply your IP address -- do online, it's a matter of a simple search. Ta-daa.
There's no getting around Google without the use of tor or anonymizing proxies, which can be annoying and slow, but using plug-ins like Track Me Not that send random search queries to Google from Firefox means that your actual search queries are mixed in with dozens of others and determining what you actually searched for becomes more challenging. Coupling that with the use of Gmail via IMAP and never logging into a Google service further reduces the amount of data that can be gathered.