The Myers-Briggs Type Indicator

The Myers-Briggs Type Indicator (MBTI) is a way of indicating how someone's brain works. The four letters each stand for a type of function. It started with a guy names Carl Jung, a Swiss psychologist who developed a theory on the differences between people. His work was later picked up by Katherine Cook Briggs and her daughter, Isabella Briggs Myers. They further developed into the indicator which is used today.

The first letter tells whether the person in introverted or extroverted, thus it is either "I" or "E".

The second letter is a bit more vauge, but it generally indicates whether the person is more focused-on-the-moment and down-to-earth, or relies more on gut instinct and thinks about possibilities. The second letter is always either an "S" for sensing, or an "N" for intuition (yes, I realize intuition doesn't start with "N", but if both the first and second letters were "I"'s, it would get confusing). This letter has the most impact on whether or not you will be able to jive well with another person. Intuiters get along well with other intuiters. Sensors get along well with other sensors. Although there won't necessarily be conflict between an S-type person and an N-type person, they won't be able to "click".

The third letter tells whether the person is emotional or not. It can be either an "F" (feeling) or a "T" (thinking) - that's pretty clear cut and simple.

The fourth letter has to do with how the person handles life. If they handle it spontaneously and take things as they come, they get a "P" (for percieving, I don't know why). If the person prefers schedules and like to plan and organize, they get a "J" (for judging, again, I don't know why it's called that).

So, four slots, two possible letters for each slot, equals a total of 16 different possible combinations, the "types". Each type is different. The four functions don't act independently of each other. Combination is important. The combinations are responsible for the fact that there are six different types of people. But, not all people of the same type are the same. Some have their auxilary more developed than others. That's where things start to get (more) complicated, so I'll leave off on the explanation here. I hope I was able to provide an understandable explanation.

If anyone is interested in this and wants to do some further reading, here are helpful links.

Know Your Type
The Myers and Briggs Foundation
Type Logic
Human Metrics Type Test (Jung)
The MBTI Instrument Overview
There's also a forum based on personality types: Personality Cafe