Is there a way to use Facebook without giving up my privacy?
Facebook is useful for keeping in touch with friends and family, but you do really have to give it all your data?
While you can choose how much information you post on Facebook, and how widely you share it, your friends may already have given Facebook your email address as part of the “find friends” procedure. Some of them may also have posted images of you, mentioned you in comments, or linked to things you posted on other services. As a result, when you sign up, Facebook may already know who most of your friends are.
Full article: Is there a way to use Facebook without giving up my privacy? | Technology | The Guardian