Each letter in the personality type code - I, N, F, and J - describes a preference for a way of thinking or behaving. There are eight styles and you use all of them, but INFJs prefer:
Introversion (thinking things through) more than Extraversion (interacting with people)
iNtuition (perceiving new possibilities) more than Sensing (perceiving tangible facts)
Feeling (making decisions using subjective values) more than Thinking (making decisions using objective logic)
Judgement (an organised lifestyle) more than Perception (a flexible lifestyle)
If your closest personality type is INFJ then you have a strong, private sense of knowledge and vision, often for hidden things that other people would think can't be known. You see imaginative possibilities and insights, especially in relation to people, anticipating a future for them that they can't even see themselves. Although you probably have some strong relationships, your insights may be so unusual that others find them difficult to accept, and you may therefore find it difficult to articulate them.
Stereotypes and Individuality
The original author of personality type theory - Carl Gustav Jung - said that everyone is individual and unique. The personality types are not strict classifications, but stereotypes that are akin to landmarks on a map. Just as a few landmarks can help you find many unique locations, so too the personality stereotypes can help you understand your unique personality.