Carl Jung was a Swiss psychiatrist and psychoanalyst who founded analytical psychology. Jung's work has been influential in the fields of psychiatry, anthropology, archaeology, literature, philosophy, psychology, and religious studies. Among the central concepts of analytical psychology is individuation—the lifelong psychological process of differentiation of the self out of everyone’s conscious and unconscious elements. Jung considered it to be the main task of human development. He created some of the best-known psychological concepts, including synchronicity, archetypal phenomena, the collective unconscious, and extraversion and introversion. Jung was also an artist, craftsman, builder, and a prolific writer. Many of his works were not published until after his death and some are still awaiting publication.