Sigmund Freud argued that personality is formed through conflicts among three fundamental structures of the human mind: the id, ego, and superego. The id is the source of instinctive and primitive behaviors governed by the pleasure principle. The ego develops to balance the id with reality. The superego incorporates societal morals and ideals which emerge around age five to influence judgment. These structures dynamically interact in complex ways to shape an individual's unique personality and behavior.