This is all you really need to know about how the different social media types work.  Brilliantly simple and yet so complex...

The infamous class notes from a student in Peter Thiel's Stanford Class on Entreprenuership & Start-ups.  These notes were later tranformed into the book "Zero To One."  Personally, I found the notes more helpful than the book (which I did read).  I think they're more telling.  And while I find some of his theories to be flawed, Thiel is a much bigger success than me so hey, beauty is all in the beholder (of the checkbook?)