Facebook friend suggestions.. how do they know?

[Persieee]

You know on the right hand corner of the facebook homepage, theres a friend suggestion box? Well how does Facebook know who I know? Sometimes there would be people from my school (network) or even through my other friends, they would be suggested there, I understand that. But, there was this kid who I haven't talked to in over 5 years, he's my dads friends son, so we're not that close, but anywho he's from Europe and I'm from the US, and well, I just liked to know how does Facebook know that I know this person?

I've never searched him on facebook, I totally forgot about him he probably forgot about me to, I've emailed him through my e-mail once probably 3 years ago. and well, let's just say we're more of acquantinces not particulary "friends".
no one on my friends list but me, plus we dont even go to school together he's from europe and i'm from the states.

[Im that one girl]

Its prolly cuz you have friends who are friends with him on there

[Kashif A]

1)If you have provided your email password (for adding Address Book of msn,yahoo,Gmail) then facebook know whoever is added in facebook, facebook would suggest you time to time that you can add this person in facebook,

2) If someone in your friend suggested that guy, you will see friend suggestion as well.

3) Facebook still needs more security , Yesterday I was reading about viewing non friend album even that person his/her security on to "ONLY FRIENDS"

[Gabe]

If theres someone that has a lot of mutual friends as you, goes to the same school or in the same network, than facebook assumes you may know them.

Please answer mine:
http://answers.yahoo.com/question/index?...749AADR8pD