MBTI (Myers-Briggs Temperament Instrument) is essentially a psychometric personality assessment based on four dichotomies of distinct orientations:
- Introverted <-> Extroverted;
- Sensing <-> Intuitive;
- Thinking <-> Feeling;
- Judging <-> Perceiving;
Each personality "type" created by this simple "pigeonholing process" leads to a general profile that can then be crafted to suit anyone who reads it for a "spiritual revival" of one's self (see Forer effect).
Due to the spiritual and artistic appreciation of personality it does not ultimately make a lot of difference unless a trained practitioner (or very knowledgeable fanatic) can make use of the psychological measurements.
In other words for example, what would (or does) your "blood type" say about or mean to you? Probably nothing, unless you researched it thoroughly and considered many angles on what it actually effects in daily real life.