The Myers-Briggs Type Indicator (MBTI) is the most widely used personality assessment instrument in the world.

• It is a 100-question personality test that asks people how they usually feel or act in particular situations.
• Respondents are classified as extraverted or introverted (E or I), sensing or intuitive (S or N),
• Thinking or feeling (T or F), and judging or perceiving (J or P).

The Myers–Briggs Type Indicator (MBTI) is an introspective self-report questionnaire with the purpose of indicating differing sociological preferences in how people behavior the world around them. 

Personality tests are kind of accurate, Myers Briggs personality test not as reliable, valid as the 'big 5' ... we know not to take them seriously, but there are others, like the mMyersBriggs type indicator (MBTI), that we trust, because a lot of psychologists once did too.

Determining Myers Briggs type indicator, your personality type is determined by your preferences. Your four dominant preferences are extraversion , sensing   feeling  and perceiving.

According to MyersBriggstheory, your personality type is inborn, and it can change. however, the way you exhibit your type will also change as you go through life.