I am beginning on using Facebook API and I have some doubts. I hope that you can help me. I want to make a Windows Phone app, and I need to authenticate each user as one. Basically I was thinking to use Facebook API to do that. But I am confused about some details: 1) Do I need to put some user data? If yes, what exactly? What do I need to store? The idea is to dispose some button linking the Facebook account with the service. And after allows the app logins automatically in this account.