What is the 'Myers–Briggs Type Indicator' used for determining?

The 'Myers–Briggs Type Indicator' (MBTI) is an introspective self-report questionnaire indicating differing psychological preferences in how people perceive the world and make decisions. The original versions of the MBTI were constructed by two Americans, Katharine Cook Briggs and her daughter, Isabel Briggs Myers.

The MBTI is based on the conceptual theory proposed by Swiss psychiatrist Carl Jung, who had speculated that people experience the world using four principal psychological functions – sensation, intuition, feeling, and thinking – and that one of these four functions is dominant for a person most of the time.

The four categories are Introversion/Extraversion, Sensing/Intuition, Judging/Perception and Thinking/Feeling. Jung's typology theories postulated each having two polar orientations (extraversion or introversion). Jung's theory of psychological types was not based on controlled scientific studies, but instead on clinical observation, introspection, and anecdote—methods regarded as inconclusive in the modern field of scientific psychology. Each person is said to have one preferred quality from each category, producing 16 unique types.

The MBTI was constructed for normal populations and emphasizes the value of naturally occurring differences. "The underlying assumption of the MBTI is that we all have specific preferences in the way we construe our experiences, and these preferences underlie our interests, needs, values, and motivation."