MBTI
A trademarked, commercially licensed personality typology (based on Jungian psychological types) that sorts people into 16 four-letter types.
MBTI-style typology scores four dichotomies, Extraversion/Introversion, Sensing/Intuition, Thinking/Feeling, Judging/Perceiving, and combines them into a 4-letter type like INTJ or ENFP. The ideas trace back to Carl Jung's early-20th-century theory of psychological types.
The official MBTI assessment itself is a trademarked, paid instrument typically administered by certified practitioners. Our own 16 Types test measures the same four dichotomies with an original questionnaire, it is informed by the general public concept of Jungian typology, but it is not MBTI and isn't affiliated with any trademark holder.