Here are what all the letters mean.
First letter: Energizing preference. Extraverts (sic) rejuvenate themselves by spending time with others; Introverts seek restoration by spending time alone. This goes well beyond "talkativeness" or "shyness." Extraverts like to partake of any activity that allows them to interact with the world around them; Introverts enjoy quiet time to themselves. Extraverts, at least in America, consist of about 3/4 of the population. For this reason, it is considered more socially acceptable to be an Extravert than an Introvert. The irony is that this preference is the least important of the four.
Second letter: Information-gathering preference. obServers (formerly called "Sensors") are "realists." They rely on their five senses to collect information as-is and believe that WYSIWYG. obServers are detail-oriented; they tend to be skilled at multi-tasking and juggling lots of data simultaneously. They are good at identifying what is good right here and right now. Their major weaknesses are that obServers often miss the big picture, and they often have difficulty understanding the implications of a given idea.
By contrast, iNtrospectives are "idealists"; they look for the hidden meanings and motives behind the brute facts. Oriented with the big picture, iNtrospectives believe that there is much more than meets the eye. They excel at driving to the heart of the matter and blowing away smokescreens and irrelevant material. Naturally, since iNtrospectives tend to be dreamers, they focus on how things should be. Therefore, their thinking is generally oriented toward the future instead of the present. iNtrospectives' major weakness is the inability to perceive the reality of the here-and-now; they have difficulty being down-to-earth. Communication between obServers and iNtrospectives is often difficult, as they see the world in fundamentally different ways. Neither way is superior in any way, but this fundamental difference makes this the most critical personality trait of the four. Also, the majority of people are obServers, so this trait is the socially acceptable one.
Third letter: Decision-making preference. obServation-vs-iNtrospection is the input preference; Tough-minded-vs-Friendly (formerly called Thinking and Feeling) is the output preference. Tough-minded people use logic to judge the quality of decisions. They place a high emphasis on truth and justice. They are willing to accept people's feelings so long as they conform to logical principles. They strive for achievements and accomplishments in their lives. Their major weakness is that they often fail to account for the effects that their decisions will have on people; thus, their decisions tend to be heartless and uncaring. They tend to forget that human beings are not rational creatures. The majority of men are Tough-minded and are easily--albeit surprisingly accurately--stereotyped into the Tough-minded preference; therefore, this is the socially acceptable trait for men.
By contrast, the primary standard of Friendly people's decisions is whether or not they are compassionate. They place a high priority on kindness and harmony, and try to go out of their way to please others. They are willing to "take one for the team" in the name of rendering kindness to another human being. They yearn for sincere acceptance and appreciation. Their major weakness is that their decisions can be highly irrational; there are times when it is necessary to be harsh, and Friendly people have difficulty in bringing themselves to do that. They are also very sensitive to criticism. The majority of women are Friendly, so this has historically been the socially acceptable trait for women. However, because of the influence of women's rights in today's society, it is becoming more socially acceptable for women to possess the Tough-minded preference.
Fourth letter: "Deciding-vs-executing" preference. This one ties the other three together (more on this in a later post). Judgers want issues settled and resolved. Incomplete jobs and unresolved matters annoys Judgers, who want the matters taken care of. They do not matter how this is done so much as the fact that it gets done. In short, Yoda's saying of "There is no try: do; or do not" appeals to Judgers. They are skilled at tying up loose ends. However, they have an unfortunate knack for doing so prematurely, before they have collected enough information to make a decision. This tends to breed a self-dilusion that they understand the situation perfectly, when at times they are well off the mark. Therefore, this can be a good trait in certain situations, but not all of them.
Probers (formerly Perceivers) want issues to be kept open and flexible. Having to finalize a scenario annoys Probers, as they they would rather continue the process of information collection instead of taking what they have and bringing forth a decision. They enjoy the startup phase of projects and are process-oriented, not task-oriented. Adabtability is a trademark trait of a Probers. Unfortuately, they have difficulty prioritizing the validity of different options and tend to fall for the dilusion that every conclusion is a good conclusion. This can cause problems in a situation where a solitary answer is required. This preference is split almost 50/50 within both gender lines and the overall population. However, because the entertainment industry is dominated by people of the SP temperment (iirc), and because of the recent surge in the ideology of tolerance, Probing appears to be the socially acceptable trait in the majority of social circles.
