> (b) There's one big difference between Facebook and generic advertising technology: the New York Times doesn't require you to sign up. > (c) Ad tracking know

> (b) There's one big difference between Facebook and generic advertising technology: the New York Times doesn't require you to sign up. > (c) Ad tracking knows which websites I visit. Facebook knows which nude parties I attended in 2005 Facebook tracks you off the site and has been known to build shadow profiles of non-users.