Madbitcoins told me about Steem. I understand enough to know I should post here.... But how does this whole thing work?

So,

This is it huh?  The future.  A time when nerds rule the Earth and computers are vital to society.  When Social Networks define a person.  "The nerdification of America".  I think the next step in the nerdification of America is digital currency.   But what is this Steem all about?  I understand some basics, I guess I am just looking for clarification.  Is this digital currencies "killer app"?  

Cheers,