How does this application in facebook work?

[♥ Καλ ♥]

Hi! There is an application in facebook that is called "your best friends forever" and it is supposed to find your best friends...The strange thing is that it has found mine and the ones of some of my friends! Something even stranger is that i rarely speak or write to these people in fb but they are my best friends in real life! I mean, we hardly communicate via facebook so as to say that the facebook "spies" on me... WHAT HAPPENS?

[Ichi]

I don't think Facebook spies on it's users. Although it's probably a coincidence.