Socionics is a theory of information processing and personality type, distinguished by its information model of the psyche, called Model A, and a model of interpersonal relations. It incorporates Carl Jung's work on Psychological Types with Antoni Kępiński's theory of information metabolism. Socionics is a modification of Jung's personality type theory that uses eight psychic functions. These functions process information at varying levels of competency and interact with the corresponding function in other individuals, giving rise to predictable reactions and impressions—a theory of intertype relations.

Socionics was developed in the 1970s and '80s, primarily by the Lithuanian researcher Aušra Augustinavičiūtė, an economist, sociologist, and dean of the Vilnius Pedagogical University's department of family science. A. Augustinavičiūtė has later shortened her last name from "Augustinavichiute" to "Augusta" to make it easier to spell for foreigners. The name "socionics" is derived from the word "society", because A. Augusta believed that each personality type has a distinct purpose in society, which can be described and explained by socionics. Augusta created symbols to represent the functions described by Carl Jung and — together with a circle of fellow researchers/hobbyists — eventually created what is known as the "socionic model of the psyche" — a description of the psyche where each of the 8 information elements has its place in each person's psyche.

The central idea of socionics is that information is intuitively divisible into eight categories, called information aspects or information elements, which a person's psyche processes using eight psychological functions. Each sociotype has a different correspondence between functions and information elements, which results in different ways of perceiving, processing, and producing information. This in turn results in distinct thinking patterns, values, and responses to arguments, all of which are encompassed within socionic type. Socionics' theory of intertype relations is based on the interaction of these functions between types.