How to get a Facebook user's ID?
<p>I followed this tutorial: <a href="http://developers.facebook.com/docs/authentication/" rel="nofollow">http://developers.facebook.com/docs/authentication/</a>
on how to setup Facebook authentication using php (server-side implementation). I can get a access token back from Facebook but how do I get the Facebook user ID of the user who has logged in?</p>
