ISTP

ISTPs lead with Introverted Thinking (Ti), which compels them to work out problems deductively inside  their own head, performing mental calculations and methodically analyzing their own reasoning and trains  of thought. They are not inclined to trust what has been worked out by other people without critiquing it  themselves, and they view facts and data as tools to measure the accuracy of their own logic. 

Their auxiliary function is Extraverted Sensing (Se), which means they are concrete thinkers who are good  at tangible logic, naturally live in the moment, and enjoy learning and utilizing different physical skills.  They are practical people who are aware of their immediate environment and are comfortable in their own  bodies, usually enjoying physical activities or games that involve hand-eye coordination. 
 

Their tertiary function is Introverted Intuition (Ni), which is where they become more interested in abstract  concepts and imagining the future. They learn to trust their hunches and to take a longer-term view of  things, and they may become more interested in ideology or philosophy, but the ideas they adopt will  usually play a supporting role to their personal experiences. They tend to speak less but with deliberation,  contemplating their words and quickly getting to the point, without going off-topic or going into great depth  about their adopted theories. 

Their inferior function is Extraverted Feeling (Fe) which is the part of the ISTP that values the feelings and  opinions of other people. They are usually unaware of how other people are likely to react to their logic and  rarely take them into consideration when actually in their own mind, and they often find social norms and  conventions confusing and alien, but they nonetheless often desire to make connections and “fit in” with  others and they like it when they feel welcomed and accepted. They can enjoy and benefit from the support  of those who are good at navigating the emotions of other people as well.  

ISTPs are problem-solvers, with a focus on practical analysis and a natural affinity for understanding how  things work. They navigate life with a sense of directness and a desire to engage with the world in a tangible  way. ISTPs excel in situations that require quick thinking and adaptability, often thriving in fields that  involve mechanics, troubleshooting, or physical skills. 

They are hands-on learners, preferring to interact directly with their environment to understand the  intricacies of its functioning. ISTPs are adept at dissecting systems, identifying issues, and applying logical  and efficient solutions. Their thinking is concrete and oriented towards action, which enables them to react  swiftly and effectively in the moment. 

In social settings, ISTPs might seem reserved or even aloof. They tend to be independent and value their  autonomy, sometimes struggling with structures and expectations that they find too constraining or  arbitrary. ISTPs bring a practical mindset to their endeavors. They are realistic about the limitations and possibilities  of their environment, and they apply this realism to achieve their goals. 

While ISTPs are usually more comfortable with what is rather than what could be, they do have an inventive  streak that allows them to think outside the box when necessary. Their grounded perspective, combined  with their willingness to experiment with new methods, makes them invaluable in many different contexts,  from crisis management to innovation in the applied sciences.