Sigmund Freud (1856-1939) was an Austrian neurologist and the founder of psychoanalysis, a groundbreaking approach to understanding the human psyche. Freud introduced concepts such as the unconscious mind, repression, and the tripartite structure of the psyche, which includes the id, ego, and superego. His work, including seminal texts like The Interpretation of Dreams and Beyond the Pleasure Principle, emphasized the role of unconscious drives and childhood experiences in shaping behavior and personality. Freuds theories on sexuality, defense mechanisms, and dream analysis challenged societal norms and profoundly altered the field of psychology, influencing literature, art, and philosophy. Though controversial, his contributions laid the foundation for modern psychotherapy and continue to spark debates and inspire new approaches to understanding human behavior and mental processes.