Psychoanalysis began in the late 19th century with Sigmund Freud who developed comprehensive theories about human nature, behavior, and the structure of the mind. Freud believed that talking about psychological problems and hidden memories could help treat mental disorders, known as the "talking cure." He identified concepts like the id, ego, and superego that make up different parts of the personality. Psychoanalysis uses techniques like free association, dream analysis, and interpretation to bring unconscious thoughts and desires into awareness to provide insight.