The whiz kid is a stock character who is highly intelligent but lacking in physical strength. They usually wear glasses and are somewhat overdressed or tout a different style than the rest of the cast (this often includes button-up shirts, suspenders, and gelled, parted hair).
The whiz kid is usually interested in books, science and technology, and more recently the stereotype has taken up interest in computers and the Internet. The whiz kid takes pride in being smart, and often uses big words (sometimes to show off, or to confuse and manipulate other, less intelligent people around them). The whiz kid usually uses his or her superior knowledge to help the main characters of a story accomplish some goal.
A whiz kid can also be intended as an exceptionally talented and comparatively young person, esp. a newcomer, who shows great promise in a particular field.