Do you use Facebook? Why or why not?

Do you use Facebook? If so, what primarily do you use it for?
If you aren’t on Facebook, what reasons do you have for abstaining? Do you ever regret not having one?

I used to have one but I jumped ship several years ago, due to friend and family drama. Also, I allowed it to be a huge distraction for me when I was writing papers >_> Finally, I am highly likely the only person on Earth with my name, and I did not like that all and sundry from my past could latch onto me on there.

The only reason I regret not having one now is that it is how people seem to plan all events. I’ve missed out on a lot of parties among my grad school cohort because they only invite people through facebook. Which strikes me as pretty rude.