My fb started with my HS friends. It was like a year-long reunion.
I confess I looked up every ex bf and friend requested them!
Then the flood of people from my original home town came, some friends from college came, all my extended family connected, all my present-day friends and people from my current town connected.
Then I started working this agent job and professional colleagues and customers started connecting.

It's a funny dynamic now because there are friends who were once punk rockers with me and there are bankers and lawyers and doctors, oh my. And some punk rockers are now lawyers...