Sigmund Freud was an Austrian neurologist who developed psychoanalysis, a method for understanding and treating mental disorders. He introduced a new approach to therapy that focused on exploring unconscious thoughts and feelings through conversation between the patient and the analyst. Freud's theories about the mind, including concepts such as the id, ego, and superego, have had a significant influence on psychology and psychiatry. His work has shaped modern views on human behavior, personality, and the treatment of psychological issues.