>>The truth is that the plethora of information Facebook knows about you is unfathomable.<p>It literally is.<p>What is really scary is that, even if you as an individual decide to withhold some information in your profile, that information can still be determined, with very high accuracy, by analyzing your friends. For example, if you don't tell Facebook where you live, someone can just use the API to analyze your new friends' locations and figure out your general geographic area.<p>Forget ads. In the grand scheme of things, ads don't matter. What matters is that there is absolutely no way anyone can use Facebook and still remain a private individual. And the implications of this are already changing society in fundamental ways (some positive, but mostly negative).