There are two groups of letters in the personality type code:
The dominant function of an ISTJ is the perceptive one of Sensing. This means you like looking at information in terms of facts and details, focusing more on the here and now rather than possibilities for the future. You feel comfortable in areas of proven experience, and take a realistic approach.
The perceptive Sensing function is introverted. That is, Sensing is used primarily to govern the inner world of thoughts and emotions. You seek to develop a realistic understanding of the world as it is, in the light of what you observe. You are pragmatic in nature, constantly learning to adapt to the world as it is now, and are continually expanding your inner store of facts, information and experience.
The diagram represents how an average ISTJ uses all the functions. You can find out more about the diagram, and your personal, unique type dynamics, by completing our personality test.
Next: How ISTJs irritate others