How does facebook determine which Friends appear on your Facebook Profile sidebar?

[Tedd]

Why do some Facebook friends appear more often on your Facebook Profile sidebar. Is there a known reason why some friends picture will show up more than others in the facebook sidebar?
Because like I have a famous celebrity always pop up on my sidebar. When I never go to their profile. So is it like they're viewing my Facebook a lot?
Or how does it work?

[TomTomB]

It's really just randomized..but sometimes it may depend on who you interact with most

[SantinaL]

Just randomly changes as time passes. Go on your profile and refresh the page after a few mins, you'll see that there's different people on top this time.

[Gloria Collins]

On your own profile page, it appears to be partly random, but I think a large factor is who you interact with (and your friends interaction with you) in terms of wall posts, comments, likes, photo tags that include you (or your photo tags that include them), etc. I would guess that wall posts, comments and photo tags play the largest roll in determining your friends sidebar.

It may also show friends whom profiles and/or pictures you view more often (or they view your profile), although this would only be one factor in the algorithm.

There's a possibility that it may also take into account and show friends who have more friends in common between you and other friends (although I doubt this is a huge factor).

Facebook will cache your friends sidebar, so if you refresh the page you may see the same friends (possibly in a different order).

Keep in mind, the exact algorithm that Facebooks uses to determine your friends sidebar is not known publicly, so this is just a best guess.

If you go on one of your friend's profile page, they tend to put friends that are closest to you in terms of friends of friends, network or mutual friends so you are more likely to know them.