Here is a very simple explanation of all the different forms of social media. I think it's super funny.
The three forms of social media I use actively are:
Twitter - @jennyjenny99 if you want to start following me.
Facebook - I have my personal page and I am working on a Minivan Stiletto page - but just not quite there yet.
Pinterest - pretty much just a collection of recipes and the odd activity / craft idea for the kids. (jennyjenny99 is you want to follow my boards).
What about you? What social media do you use?