A pioneering figure in the development of modern psychology is Sigmund Freud, renowned for establishing the basis of psychoanalysis. Freud's theories on the unconscious mind, dreams, and human behavior revolutionized psychology, influencing both treatment approaches and theoretical perspectives. He introduced key concepts such as libido, repression, and defense mechanisms, shaping our understanding of mental health. Freud's impact extends beyond psychology, affecting literature, art, and cultural studies, leaving a complex and lasting legacy in exploring the human psyche.