What is "istj"

ISTJ (By functions; Introverted Sensing (Si), Extroverted Thinking (Te), Introverted Feeling (Fi) and Extroverted Intuition (Ne)) is an abbreviation used in the publications of the Myers–Briggs Type Indicator (MBTI) to refer to one of sixteen personality types. The MBTI assessment was developed from the work of prominent psychiatrist Carl G. Jung in his book Psychological Types. Jung proposed a psychological typology based on the theories of cognitive functions that he developed through his clinical observations.

From Jung's work, others developed psychological typologies. Jungian personality assessments include the MBTI assessment, developed by Isabel Briggs Myers and Katharine Cook Briggs, and the Keirsey Temperament Sorter, developed by David Keirsey. Keirsey referred to ISTJs as Inspectors, one of the four types belonging to the temperament he called the Guardians. ISTJs account for about 10–14% of the population.