Sigmund Freud (1856-1939) was an Austrian neurologist and the founder of psychoanalysis, a revolutionary approach to understanding and treating mental disorders. Freud developed groundbreaking theories on the unconscious mind, arguing that unconscious thoughts and desires shape human behavior. He introduced concepts such as the Oedipus complex, repression, and the three-part structure of the psyche—the id, ego, and superego. Freud's innovative therapeutic technique, the "talking cure," involved patients discussing their experiences and emotions to uncover unconscious conflicts.