The popular understanding of what is it to be a ‘nerd’ is not right. I’m not saying that people are using the word differently than defined: I’m saying that I don’t think the current definition is quite what it should be. Google calls a nerd: “an intelligent, single-minded expert in a particular technical discipline or profession”. Wikipedia says: “Nerd is a term that refers to an intelligent but single-minded person obsessed with a nonsocial hobby or pursuit”. My definition of nerdiness (which I believe I came to through Marco) is along the same lines. But it’s a bit simpler.
As far as I’m concerned, a nerd is simply someone who cares about something more than most other people. And you say nerds are nerdy about that particular thing.
You can be nerdy about computers, of course. You can be nerdy about roleplaying games. Obviously. But I also think you can be nerdy about trains and aeroplanes, about television, about music, about beer, about cider, about coffee, about cinema, about books. About just about anything.
I’m a huge nerd. It stems from the sort of personality I have (or the sort of personality that I am, if you like to think of things that way). I care about things. If somethings worth doing, it’s worth caring about doing it right. If I enjoy something, I want to get optimal enjoyment, so I find out the best way to do that. I care.
Nerds are the best kind of people.