Here's what Wikipedia says about INTP:
INTP - The ThinkersThe logical and analytical type. They are especialy attuned to difficult creative and intellectual challenges and always look for something more complex to dig into. They are great at finding subtle connections between things and imagine far-reaching implications.
They enjoy working with complex things using a lot of concepts and imaginative models of reality. Since they are not very good at seeing and understanding the needs of other people, they might come across as arrogant, impatient and insensitive to people that need some time to understand what they are talking about.
INTP types are quiet, thoughtful, analytical individuals who don't mind spending long periods of time on their own, working through problems and forming solutions. They are very curious about systems and how things work, and are frequently found in careers such as science, architecture and law. INTPs tend to be less at ease in social situations and the "caring professions," although they enjoy the company of those who share their interests. They also tend to be impatient with the bureaucracy, rigid hierarchies, and politics prevalent in many professions, preferring to work informally with others as equals.
INTPs organize their understanding of any topic by articulating principles, and they are especially drawn to theoretical constructs. Having articulated these principles for themselves, they can demonstrate remarkable skill in explaining complex ideas to others in simple terms, especially in writing. On the other hand, their ability to grasp complexity may also lead them to provide overly detailed explanations of "simple" ideas, and listeners may judge that the INTP makes things more difficult than they are. This to the INTP, however, is incomprehensible: They are merely presenting all of the information.
INTPs' extraverted intuition often gives them a quick wit, especially with language, and they can defuse the tension in gatherings by comical observations and references. They can be charming, even in their quiet reserve, and are sometimes surprised by the high esteem in which their friends and colleagues hold them.
When INTPs feel insulted, however, they may respond with sudden and crushing criticism. After such an incident, INTPs are likely to be as bewildered as the recipient. They have broken the rules of debate and exposed their raw emotions. This to an INTP is the crux of the problem: their emotions are to be dealt with in a logical manner. If improperly handled, they can only harm.
My overall personality type from a few different, informal MBTI tests suggest that I'm ENTP. It seems to be more predictive of me, with a bit of INTP showing up when I go through my rare quiet times.
Here's what Wikipedia says about ENTP:
Still, I'd like to step outside of both these styles to stretch my writing capability. One interesting thing I saw in myself while looking at the MBTI type descriptions -- aspects of Judging are offensive to me. Not people with those traits, per se, but those traits in my personality. I actively eliminate them when I discover them.
The ENTP has been described variously as the innovator, the originator, the lawyer, the inventor, the explorer, and the visionary. ENTPs also fall into the general categories of thinkers, rationals, and engineers. Using their primary function-attitude of extraverted intuition (Ne), ENTPs are quick to see complex interrelationships between people, things, and ideas. These interrelationships are analyzed in profound detail through the ENTPs auxiliary function, introverted thinking (Ti). The result is an in-depth understanding of the way things and relationships work, and how they can be improved. To the ENTP, competence and intelligence are particularly prized, both in themselves and in other people.
ENTPs are frequently described as clever, cerebrally and verbally quick, enthusiastic, outgoing, innovative, flexible, loyal and resourceful. ENTPs are motivated by a desire to understand and improve the world they live in. They are usually accurate in sizing up a situation. They may have a perverse sense of humor and sometimes play devil's advocate, which can create misunderstandings with friends, coworkers, and family. ENTPs are ingenious and adept at directing relationships between means and ends. ENTPs "think outside the box," devising fresh, unexpected solutions to difficult problems. However, they are less interested in generating and following through with detailed plans than in generating ideas and possibilities. When ENTPs are used correctly on a team, they offer deep understanding and a high degree of flexibility and problem solving ability. The ENTP regards a comment like "it can't be done" as a personal challenge, and, if properly motivated, will spare no expense to discover a solution.
Hat-tip to my friend Unacoder