The Zuckopticon

Nik Cubrilovic has discovered how Facebook's "Logout" is not logging you out:

Logging out of Facebook only de-authorizes your browser from the web application, a number of cookies (including your account number) are still sent along to all requests to facebook.com. Even if you are logged out, Facebook still knows and can track every page you visit. The only solution is to delete every Facebook cookie in your browser, or to use a separate browser for Facebook interactions.

This is not what 'logout' is supposed to mean - Facebook are only altering the state of the cookies instead of removing all of them when a user logs out.

With my browser logged out of Facebook, whenever I visit any page with a Facebook like button, or share button, or any other widget, the information, including my account ID, is still being sent to Facebook. The only solution to Facebook not knowing who you are is to delete all Facebook cookies.

In a way, you can see why Facebook is doing this: to preserve your state in order to connect your clicking of "Like" to your profile. However, it challenges the ethics of privacy and what "Logout" means. 

Surely Facebook knows this. The question must surely be how, now, it must communicate this situation to its millions of users.