Psychoanalytic theory proposes that personality is determined by unconscious desires, motivations, and childhood experiences. It guides psychoanalysis, a clinical method developed by Sigmund Freud to treat psychopathology by exploring the unconscious mind through techniques like free association, dream interpretation, and analysis of defenses. Key concepts in psychoanalytic theory include the id, ego, and superego; psychosexual stages of development; and defense mechanisms used to resolve conflicts between unconscious and conscious desires.