I'm an ESTP - Extroverted, Sensing, Thinking, Perceiving. I think this definition fits me pretty well.
As an ESTP, your primary mode of living is focused externally, where you take things in via your five senses in a literal, concrete fashion. Your secondary mode is internal, where you deal with things rationally and logically.
ESTPs are outgoing, straight-shooting types. Enthusiastic and excitable, ESTPs are "doers" who live in the world of action. Blunt, straight-forward risk-takers, they are willing to plunge right into things and get their hands dirty. They live in the here-and-now, and place little importance on introspection or theory. The look at the facts of a situation, quickly decide what should be done, execute the action, and move on to the next thing.
ESTPs have an uncanny ability to perceive people's attitudes and motivations. They pick up on little cues which go completely unnoticed by most other types, such as facial expressions and stance. They're typically a couple of steps ahead of the person they're interacting with. ESTPs use this ability to get what they want out of a situation. Rules and laws are seen as guidelines for behavior, rather than mandates. If the ESTP has decided that something needs to be done, then their "do it and get on with it" attitude takes precendence over the rules. However, the ESTP tends to have their own strong belief in what's right and what's wrong, and will doggedly stick to their principles. The Rules of the Establishment may hold little value to the ESTP, but their own integrity mandates that they will not under any circumstances do something which they feel to be wrong.
ESTPs have a strong flair for drama and style. They're fast-moving, fast-talking people who have an appreciation for the finer things in life. They may be gamblers or spendthrifts. They're usually very good at story telling and improvising. They typically makes things up as they go along, rather than following a plan. They love to have fun, and are fun people to be around. They can sometimes be hurtful to others without being aware of it, as they generally do not know and may not care about the effect their words have on others. It's not that they don't care about people, it's that their decision-making process does not involve taking people's feelings into account. They make decisions based on facts and logic.
ESTP's least developed area is their intuitive side. They are impatient with theory, and see little use for it in their quest to "get things done". An ESTP will occasionally have strong intuitions which are often way off-base, but sometimes very lucid and positive. The ESTP does not trust their instincts, and is suspicious of other people's intuition as well.
The ESTP often has trouble in school, especially higher education which moves into realms where theory is more important. The ESTP gets bored with classes in which they feel they gain no useful material which can be used to get things done. The ESTP may be brilliantly intelligent, but school will be a difficult chore for them.
The ESTP needs to keep moving, and so does well in careers where he or she is not restricted or confined. ESTPs make extremely good salespersons. They will become stifled and unhappy dealing with routine chores. ESTPs have a natural abundance of energy and enthusiasm, which makes them natural entrepreneurs. They get very excited about things, and have the ability to motivate others to excitement and action. The can sell anyone on any idea. They are action-oriented, and make decisions quickly. All-in-all, they have extraordinary talents for getting things started. They are not usually so good at following through, and might leave those tasks to others. Mastering the art of following through is something which ESTPs should pay special attention to.
ESTPs are practical, observant, fun-loving, spontaneous risk-takers with an excellent ability to quickly improvise an innovative solution to a problem. They're enthusiastic and fun to be with, and are great motivators. If an ESTP recognizes their real talents and operates within those realms, they can accomplish truly exciting things.