Can anyone tell me what the point of Facebook is?

Seriously. Thats all. I am staring at it, and I am poking it, and I am entering the names of all the names of anyone I have ever known into it (who either must be too old or luddites or hiding, for I cannot find them) and I cannot for the life of me work out what the point is.

Can anyone tell me what the point is? Please?