One useful thing to note is that a gigantic amount of information is publicly accessible, but in one or more of the following states: * Requires effort to acce

One useful thing to note is that a gigantic amount of information is publicly accessible, but in one or more of the following states: * Requires effort to access * Is in out-of-the-way places many people don't know about * Is in a form that's difficult to consume Even though it's "public", in many ways it behaves as if it isn't, since until one of those conditions is removed people don't really bother to access it, pay attention to it, or try to consume it. In other words, it's one of those "if a tree falls in the forest and nobody's around to hear it" situations. So information which is only available to someone with an account, but on a system which grants accounts for free to anyone who wants one, typically is thus seen as "private" or at least in a "not really public" state until such time as someone massively aggregates it and makes it available to people without accounts, as happened with OKCupid.