Log in facebook in parse allows for read permissions. This doesn’t require to launch facebook app. Simple popup allows this. Instead does everything in the background. We can pull fb user’s id, name etc. with this. We can then link this to PFuser object in our User table. Parse allows devellopers to store and link uploaded photos by users on Parse. This opens up freedom to create applications to have linked users (by facebook) on Parse. One scenario:

            User A logs in with facebook on app X. App X grabs all of his fb
            friend list and save it to Parse. Then, his friend user B logs
            in with facebook using app X. This gives us possibility to send
            a notification to the user A saying, your friend just joined the
            app. 

Birthdays:

      Login with facebook, your friends birthday and get automatic
      notification to your phone.