How To find Facebook ID

Facebook ID is a unique number identifying a Facebook profile, Facebook groups or fan pages. There is two way of finding Facebook user id either using Javascript or Facebook Graph.
1. Find UID using JavaScript:

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.