Nerd a pretty common word with vivid connotations. I thought I'd avoid the Nerd vs Geek vs Dork debate, since all of them were pretty interchangeable at my school and I fit all three.
Basically, all three denote an obsession or passion that overshadows permissible social conduct. It could be math, fantasy, sci-fi, books, writing, art, animals, anything. The term 'nerd' generally applies to people who obsess of things out of the mainstream, because to obsess about puppies or certain popular television shows is permissible social conduct.
Obsessing about the latest Dragon Age expansion pack? Not so much.
There are a lot of stereotypes in the world, which we pretty much all know. Anyone who ever took a quiz on quizilla or facebook or myspace (depending on your generation) knows that classification is a must in our society. "You have a green spirit," or "Your Personality Color is Pink" can often translate to "You're a nature geek," or "You're a prep!"
In our culture, the only acceptable solution to stereotypes is to run away from them. "Don't classify me, man!" which has given rise to dozens of sub-cultures that, in the end, really only stereotype the people in them (hipsters, for example).
But is running from stereotype the right decision?
Once I embraced my status as a 'nerd', I was free. In a paradoxical way, when I had settled into my niche, I could travel outside it without being labeled. When I tried dance, sports, clubs, mall-hopping (that phase didn't last long), no one thought anything about it. I knew I was a nerd, I loved being a nerd, and no matter what I looked like on the outside, at the end of the day, I was still a nerd.
Not that you can't change your stereotype. You just don't have to. Nerds can be jocks, skaters can be ballerinas, musicians can be preps.
Maybe the world would be more ideal without stereotypes, but we're stuck with them for now. Why not embrace it?