INTJs live in the world of ideas and strategic planning. We value intelligence, knowledge, and competence, and typically have high standards in these regards, which we continuously strive to fulfill. To a somewhat lesser extent, we have similar expectations of others.
With Introverted Intuition dominating our personality, INTJs focus their energy on observing the world, and generating ideas and possibilities. Our mind constantly gathers information and makes associations about it. We are tremendously insightful and usually are very quick to understand new ideas. However, our primary interest is not understanding a concept, but rather applying that concept in a useful way. Unlike the INTP, we do not follow an idea as far as they possibly can, seeking only to understand it fully. INTJs are driven to come to conclusions about ideas. Their need for closure and organization usually requires that they take some action.
INTJ's tremendous value and need for systems and organization, combined with our natural insightfulness, makes us excellent scientists. An INTJ scientist gives a gift to society by putting our ideas into a useful form for others to follow. It is not easy for us INTJs to express our internal images, insights, and abstractions. The internal form of the INTJ's thoughts and concepts is highly individualized, and is not readily translatable into a form that others will understand. However, the INTJ is driven to translate our ideas into a plan or system that is usually readily explainable, rather than to do a direct translation of our thoughts. We usually don't see the value of a direct transaction, and will also have difficulty expressing our ideas, which are non-linear. However, our extreme respect of knowledge and intelligence will motivate them to explain themselves to another person who they feel is deserving of the effort.
INTJs are natural leaders, although we usually choose to remain in the background until we see a real need to take over the lead. When we are in leadership roles, we are quite effective, because we are able to objectively see the reality of a situation, and are adaptable enough to change things which aren't working well. We are the supreme strategists - always scanning available ideas and concepts and weighing them against our current strategy, to plan for every conceivable contingency.
INTJs spend a lot of time inside our own minds, and may have little interest in the other people's thoughts or feelings. Unless our Feeling side is developed, we may have problems giving other people the level of intimacy that is needed. Unless our Sensing side is developed, we may have a tendency to ignore details which are necessary for implementing their ideas.
The INTJ's interest in dealing with the world is to make decisions, express judgments, and put everything that they encounter into an understandable and rational system. Consequently, we are quick to express judgments. Often we have very evolved intuitions, and are convinced that we are right about things. Unless we complement our intuitive understanding with a well-developed ability to express our insights, we may find ourselves frequently misunderstood. In these cases, INTJs tend to blame misunderstandings on the limitations of the other party, rather than on our own difficulty in expressing ourselves. This tendency may cause the INTJ to dismiss others input too quickly, and to become generally arrogant and elitist.
INTJs are ambitious, self-confident, deliberate, long-range thinkers. Many INTJs end up in engineering or scientific pursuits, although some find enough challenge within the business world in areas which involve organizing and strategic planning. We dislike messiness and inefficiency, and anything that is muddled or unclear. We value clarity and efficiency, and will put enormous amounts of energy and time into consolidating their insights into structured patterns.
Other people may have a difficult time understanding an INTJ. People may see us as aloof and reserved. Indeed, the INTJ is not overly demonstrative of their affections, and is likely to not give as much praise or positive support as others may need or desire. That doesn't mean that he or she doesn't truly have affection or regard for others, we simply do not typically feel the need to express it. Others may falsely perceive the INTJ as being rigid and set in their ways. Nothing could be further from the truth, because the INTJ is committed to always finding the objective best strategy to implement their ideas. The INTJ is usually quite open to hearing an alternative way of doing something.
When under a great deal of stress, the INTJ may become obsessed with mindless repetitive, Sensate activities, such as over-drinking. We may also tend to become absorbed with minutia and details that we would not normally consider important to their overall goal.
INTJs need to remember to express ourselves sufficiently, so as to avoid difficulties with people misunderstandings. In the absence of properly developing their communication abilities, we may become abrupt and short with people, and isolationists.
INTJs have a tremendous amount of ability to accomplish great things. We have insight into the Big Picture, and are driven to synthesize our concepts into solid plans of action. Our reasoning skills gives us the means to accomplish that. INTJs are most always highly competent people, and will not have a problem meeting our career or education goals. We have the capability to make great strides in these arenas. On a personal level, the INTJ who practices tolerances and puts effort into effectively communicating our insights to others has everything in his or her power to lead a rich and rewarding life.
Copied from: http://www.personalitypage.com/html/INTJ.html