Most of the info is not publicly available but collected by inferring information about based on the pages you visit, who you talk and which other users you associate with.
I think that is in reference to Facebook mining your DMs and web searches, neither of which are viewable to your FB friends or other internet users at large. FB accesses any and everything they can regarding your browsing behavior and ends up with far more data about a user than what is displayed publicly on the user’s public profile.
