A complex is a structure in the unconscious that is objectified as an underlying theme—like a power or a status—by grouping clusters of emotions, memories, perceptions and wishes in response to a threat to the stability of the self. In psychoanalysis, it is antithetical to drives.
An example of a complex would be as follows: if a person had a leg amputated when a child, this would influence the person's life in profound ways, even upon overcoming the physical handicap. The person may have many thoughts, emotions, memories, feelings of inferiority, triumphs, bitterness, and determinations centering on that one aspect of life. If these thoughts were troubling and pervasive, Jung might say the person had a "complex" about the leg.
The reality of complexes is widely agreed upon in the area of depth psychology, a branch of psychology asserting that the vast majority of the personality is determined and influenced by unconscious processes. Complexes are common features of the psychic landscape, according to Jung's accounting of the psyche, and often become relevant in psychotherapy to examine and resolve, most especially in the journey toward individuation or wholeness. Without resolution, complexes continue to exert unconscious, maladaptive influence on our thoughts, feelings, and behavior and keep us from achieving psychological integration.
Carl Jung distinguished between two types of unconscious mind: the personal unconscious and collective unconscious. The personal unconscious was the accumulation of experiences from a person's lifetime that could not be consciously recalled. The collective unconscious, on the other hand, was a sort of universal inheritance of human beings, a "species memory" passed on to each of us, not unlike the motor programs and instincts of other animals. Jung believed the personal unconscious was dominated by complexes.
The term complex (Komplex; also emotionally charged complexes or feeling-toned complex of ideas), was coined by Carl Jung when he was still a close associate of Sigmund Freud.