The Keirsey Temperament Sorter is a self-assessed personality questionnaire designed to help people better understand themselves and others. More at Wikipedia
Myers-Briggs Type Indicator - The Myers-Briggs Type Indicator assessment is a psychometric questionnaire designed to measure psychological preferences in how people perceive the world and make decisions.
Analytical Psychology - Analytical psychology is the school of psychology originating from the ideas of Swiss psychiatrist Carl Jung, and then advanced by his students and other thinkers who followed in his tradition.
Carl Jung - Carl Gustav Jung was a Swiss psychiatrist, an influential thinker and the founder of analytical psychology.
Temperament - In psychology, temperament refers to those aspects of an individual's personality, such as introversion or extroversion, that are often regarded as innate rather than learned.
Four Temperaments - Four Temperaments is a theory of psychology that stems from the ancient medical concept of humorism, or "humours" in UK English.
Five Temperaments - Five temperaments a theory in psychology, that expands upon the "Four Temperaments" proposed in ancient medical theory.
Interaction Styles - Interaction Styles are groupings of the 16 types of the MBTI instrument of psychometrics and Jungian psychology.