20th Century Existentialism is a philosophical movement that emphasizes individual freedom, choice, and the search for meaning in an indifferent or absurd universe. Key figures include Jean-Paul Sartre, Simone de Beauvoir, and Albert Camus, who explored themes of existence, authenticity, and the human condition. This movement arose in response to the disillusionment following World War I and World War II, challenging traditional values and questioning the nature of existence. Existentialists argue that individuals must create their own meaning and navigate the complexities of life without relying on external authorities or predetermined paths.