Sigmund Freud is an Austrian neurologist widely regarded as the founder of psychoanalysis and one of the most influential figures in the history of psychology. Born in Freiberg, Moravia (now the Czech Republic), he spent most of his career in Vienna, where he developed groundbreaking theories on the unconscious mind, dreams, and human sexuality that reshaped the understanding of human behavior and mental illness. He is remembered for works including The Interpretation of Dreams, The Ego and the Id, and Civilization and Its Discontents, texts that continue to be studied as foundational works of psychology, though many of his specific theories have since been widely debated and revised by later researchers. His concepts, including the unconscious, repression, and the id, ego, and superego, introduced a new vocabulary for understanding the human mind that extended far beyond clinical psychology into literature, art, and popular culture. Forced to flee Vienna for London after the Nazi annexation of Austria in 1938, he spent his final year of life in exile before his death in 1939. Known for his pioneering, often controversial exploration of the unconscious mind, sexuality, and human behavior, Freud's work continues to shape modern psychology and cultural thought and remains a subject of study and debate across the world.