Each letter in the personality type code - I, S, T, and P - describes a preference for a way of thinking or behaving. There are eight styles and you use all of them, but ISTPs prefer:
Introversion (thinking things through) more than Extraversion (interacting with people)
Sensing (perceiving tangible facts) more than iNtuition (perceiving new possibilities)
Thinking (making decisions using objective logic) more than Feeling (making decisions using subjective values)
Perception (a flexible lifestyle) more than Judgement (an organised lifestyle)
If your closest personality type is ISTP then you have both a logical and a practical mind and therefore enjoy solving tangible problems. You are very interested in how things work, and may have a tendency to take things apart if you don't know how they work. You may also enjoy using your craftmanslike skills to fix things that are broken, or doing investigative work, collecting facts and clues to find out the truth of what has happened.
Stereotypes and Individuality
The original author of personality type theory - Carl Gustav Jung - said that everyone is individual and unique. The personality types are not strict classifications, but stereotypes that are akin to landmarks on a map. Just as a few landmarks can help you find many unique locations, so too the personality stereotypes can help you understand your unique personality.