In the Myers-Briggs Type Indicator (MBTI), an introvert (I) is a person who prefers to process thoughts internally. Introverts tend to think before they speak. It is contrasted with extroversion. The word is also used informally to refer to somebody who prefers solitary activities to social ones, which is more of a behavioural than cognitive definition.
Introverts tend to be seen as quiet and reserved, which is often confused with a lack of confidence by louder, more extroverted people. They often perform well in analytical roles that require intelligence or logic, but place less emphasis on social interactions and "people skills".