Nerd

A derogatory term to describe someone who is obsessed about the the details of a topic that seems irrelevant or trivial to other people.

For example someone who can quote the clock frequencies of every microprocessor ever made by Intel. That could be said to be 'nerdy'.

The description is also used to suggest they have no social life either because of their obsession to detail.

However, some people like to call themselves nerds and are proud of it!

Very similar in meaning to the word 'geek' except nerds can be related to any topic rather than just technology.