According to Jung's typology all people can be classified using three criteria. The extrovert has a source and direction of energy expression mainly in the external world while the introvert has a source of energy mainly in the internal world. The second criterion defines the method of information perception by a person. The third criterion defines the way of information processing. Thinking means that a person makes a decision mainly according to logic.
Feeling means that a person, as a rule, makes a decision basing on emotions.
The fourth criterion defines a way of implementation of processed information. Perceiving means that a person is inclined to improvization and seeking different alternatives. The different combinations of the criteria determine a type. There may be sixteen types. Then the corresponding type description can be represented.