Carl Gustav Jung (/jʊŋ/; German: [ˈkarl ˈɡʊstaf jʊŋ]), often referred to as C. G. Jung, was a Swiss psychiatrist and psychotherapist who founded analytical psychology. Jung proposed and developed the concepts of extraversion and introversion; archetypes, and the collective unconscious. His work has been influential in psychiatry and in the study of religion, philosophy, archeology, anthropology, literature, and related fields. He was a prolific writer, many of whose works were not published until after his death.