Final answer:
Jung proposed eight psychological types based on extraversion and introversion, describing how individuals derive their energy and approach towards life.
Step-by-step explanation:
Jung proposed eight psychological types, based on the interactions of the extraversion and introversion. These two attitudes or approaches towards life describe how individuals derive their energy - either from being outgoing and socially oriented (extraversion) or from their inner psychic activity (introversion). Jung believed that a balance between extroversion and introversion best served the goal of self-realization. These ideas are now considered to be Jung's most important contributions to the field of personality psychology.