1. Ti – internal Thinking
Ti makes decisions based on logical analysis done over time in their head. Because it is the TiSe’s strongest preference, the functions below are said to “serve” the Ti. This just means that the Ti way of doing things gets priority most of the time.

2. Se – external Sensing.
Se is the main way TiSe’s take in information. It means they use their senses to understand the world around them. They live in the moment and prefer dealing with things that are real and solid over the purely theoretical.

3. Ni – internal iNtuition.
Ni is the TiSe’s third function, and it allows them to pull from every area in their brain to find solutions to problems, to look for patterns in the information they gather, or to skip ten steps ahead and predict what will happen in the future. Ni makes the Ti-led internal world very abstract and can involve lots of jumping around on intuitive leaps. This can make it hard for TiSe’s to fully explain the method they used to reach a certain conclusion.

4. Fe – external Feeling.
Fe is the TiSe’s last function. As a last function, it is inherently not as strong as the other functions. Fe is the TiSe’s humanitarian side. It causes them to want to use their intelligence and creative problem-solving to help others and fix the world in some way. Having Fe last means that TiSe’s start out life being less aware of and equipped to deal with feelings than other types.