Freudian theory, developed by Sigmund Freud, is a psychological framework that emphasizes the influence of the unconscious mind on behavior. Freud proposed that human personality is structured into three parts: the id, which represents primal desires; the ego, which mediates between the id and reality; and the superego, which embodies moral standards. Freud also introduced concepts such as defense mechanisms, which are unconscious strategies used to cope with anxiety, and the importance of early childhood experiences in shaping personality. His theories laid the groundwork for modern psychology, despite being controversial and widely debated.