Psychoanalytic theory, developed by Sigmund Freud, explores the unconscious mind's influence on behavior and thought. It introduces concepts like the id, ego, superego, psychosexual development, and defense mechanisms to explain human psychology and personality formation. Key figures like Jung, Adler, and Klein expanded on Freud's ideas. The theory has been applied to literature, analyzing characters' motivations and authors' unconscious desires. Despite critiques, psychoanalytic concepts continue to influence psychology, therapy, and cultural analysis.