According to dictionary a person who is foolish, unfashionable, single minded or clumsy is called a geek or a nerd, but in fact the meaning of geek has changed with time.
The words geek and nerd are slang terms, which has different meanings. Nowadays these terms are generally used to mention a technical person or a computer expert.
Computer Geek: A computer expert or a person having a good amount of knowledge in the computer and/or IT field.
Note: The term “Geek” is often used implicitly for “Computer Geek”.