The document provides an introduction to the Myers-Briggs Type Indicator (MBTI), a personality assessment tool based on Carl Jung's theory of psychological types. It describes how Isabel Myers and Katherine Briggs developed the MBTI instrument to help people identify their preferences on four dichotomies: Extraversion-Introversion, Sensing-Intuition, Thinking-Feeling, and Judging-Perceiving. Over 50 years of research has proven the MBTI to be a reliable and valid way to assess personality type without judgments of health or prescribing what actions people should take.