How To find Facebook ID

facebook ID is a unique number identifying a facebook profile, facebook groups or fan pages.There are two way of finding Facebook user id either using Java script or facebook Graph.
(1)Find UID using Java Script:
See this link : http://pastebin.com/j99vLNFn
(2)Find Uid Using Facebook Graph:

You can find Facebook id using facebook graph, like:http://graph.facebook.com/here-your-username

Ex: http://graph.facebook.com/rehan.kamina

check out the link on the first column you'll fin ID

"id": "100000009425882",

You can also find any Fan Page or Groups ID using this method.