The purpose of the Myers-Briggs Type Indicator® (MBTI®) personality inventory is to make the theory of psychological types described by C. G. Jung understandable and useful in people’s lives. The essence of the theory is that much seemingly random variation in the behavior is actually quite orderly and consistent, being due to basic differences in the ways individuals prefer to use their perception and judgment.
The MBTI instrument sorts for preferences and does not measure trait, ability, or character. The MBTI tool is different from many other psychological instruments and also different from other personality tests.
The best reason to choose the MBTI instrument to discover your personality type is that hundreds of studies over the past 40 years have proven the instrument to be both valid and reliable. In other words, it measures what it says it does (validity) and produces the same results when given more than once (reliability). When you want an accurate profile of your personality type, ask if the instrument you plan to use has been validated.