Type is more than just the sum of the four preferences. The four-letter MBTI type formula is a shorthand way of telling you about the interaction of your four mental functions and which ones you prefer to use first. This is called type dynamics, and it is an important part of understanding your MBTI® results. Below are some basic facts about type dynamics.

• One preference has the most influence on you. This is called the dominant function.
  
  
• The next strongest preference is called the auxiliary function. It is important because it serves to support and balance the dominant.



• The third strongest is the tertiary function.



• One preference is the least strong. This is the fourth function, often called the inferior function.



• There is one preference each person tends to show first to the outside world.



• The eight function-attitudes are expressed very differently in the inner world and the outer world.



• The middle two preferences are called the function pair.



• Over the course of your life, different preferences may emerge and be used more often, as well as more easily. This is referred to as type development.