ISTP (personality type)
Introverted Sensing Thinking Perceiving (ISTP) is one of the sixteen personality types of the Myers-Briggs Type Indicator (MBTI), and the Keirsey Temperament Sorter.
Referring to Keirsey, ISTPs belong to the Artisan temperament and are called "Crafters"..

# Myers-Briggs Characteristics
According to Myers-Briggs, ISTPs excel at analyzing situations to reach the heart of a problem so that they can swiftly implement a functional repair, making them ideally suited to the field of engineering.  Naturally quiet people, they are interested in understanding how systems operate, focusing on efficient operation and structure.  They are open to new information and approaches.  But contrary to their seemingly detached natures, ISTPs are often capable of humorously insightful observations about the world around them, and can be closet "daredevils" who gravitate toward fast-moving and/or risky hobbies (such as bungee jumping, hang gliding, motorcycling, parachuting, SCUBA diving, etc.), recreational sports (such as downhill skiing, ice hockey, racing, etc.), and careers (such as aviation, firefighting, etc.).

# Keirsey Characteristics
According to Keirsey, ISTPs, or "Crafter Artisans", are masters at using tools of every typeartistic, technological, martial.  Although they are introverts, they are authoritarian in their interactions with others and can be forceful at influencing people. They focus on accomplishing tasks efficiently and skillfully.
To master the tool of their interest, ISTPs require a certain degree of seclusion in which to practice. The result is often a virtuosity that other types find difficult to match.

# MBTI cognitive functions
The attributes of each personality form a hierarchy.  This represents the person's "default" pattern of behavior in their day to day life. The Dominant is the personality type's preferred role, the task they feel most comfortable with.  The auxiliary function is the role they feel the next most comfortable with.  It serves to support and expand on the dominant function.  One of these first two will always be an information gathering function (sensing or intuition) and the other will be a decision making function(thinking or feeling) in some order. The tertiary function is less developed than the Dominant and Auxiliary functions, but develops as the person matures and provides roundness of ability.  The inferior function is the personality types Achilles heel. This is the function they are least comfortable with. Like the tertiary function, this function strengthens with maturity.
- Dominant Introverted Thinking-The ISTP lives a world of logic, basing any decision on logic. They process information from their auxiliary function to create strategies for action at a moment's notice. They love to examine complicated systems.
- Auxiliary Extroverted Sensing-This function gives the ISTP an element of spontaneity, embracing chances to plunge headfirst into experiences. It also gives them a keen insight into situations similar to that of the ISTJ. Their occasionally tunnelvisioned curiosity for the world around them gives them a "leap before you look" tendency. They are notorious for taking apart devices to "see what makes them tick", before consideration as to whether they can put them back together.
- Tertiary Introverted iNtuition-Never as open in their theorizing as the INTP, the ISTP prefers to keep themselves grounded in the situation at hand, using their intuition to visualize components and concepts that they cannot see and touch firsthand, such as the wiring in a circuit board.
- inferior Extroverted Feeling- The weak point of the ISTP, they may interpret criticisms of their ideas as criticisms of their competence.  While they strive to follow the edicts of logic, this can also lead them to ironically and illogically stubbornly cling to their own ideas even when proven wrong.