A word originally coined by Dr Seuss (king nerd himself), meaning someone who is smart. It is now usually used to desribe someone with more knowledge about computers than the average schmuck. Note, there IS a difference between a geek and a nerd. Geek's wish they were as good as nerd's, but at the end of they day, they are just second rate try-hard Nerds.
NERD - A term coined in the 1980s to describe intelligent but socially inept people. The term is often associated with Bill Gates. It has fallen out of favor somewhat, replaced by geek as a more up-to-date term for computer fanatics.