extraversion vs. introversion, sensing vs. intuition, thinking vs. feeling, and judging vs. perceiving. These preferences combine to form one of 16 possible personality types. According to various sources, the most common personality type on the MBTI test is ISFJ, which stands for Introverted, Sensing, Feeling, and Judging. On the other hand, the least common personality type is INFJ, which stands for Introverted, Intuitive, Feeling, and Judging. It is important to note that only the individual can decide which personality type fits them best, and over 90% of people agree with at least three out of the four preferences in their whole type.