Existentialism is a philosophical and literary movement that focuses on individual freedom, self-awareness, and the search for meaning in a seemingly indifferent and irrational universe. It emerged in the 19th and 20th centuries, with key figures including Jean-Paul Sartre, Simone de Beauvoir, and Albert Camus. Existentialism emphasizes the individual's responsibility for creating their own values and defining their own essence. It also explores the themes of authenticity, choice, and the anxiety that comes with the realization of one's own mortality. Existentialist thinkers often reject traditional philosophical ideas and religious beliefs, instead embracing the inherent ambiguity and uncertainty of human existence. They argue that the only source of meaning in life is the individual's own subjective understanding and experience. Overall, existentialism encourages individuals to confront the challenges and absurdities of existence with courage and integrity, and to live authentically in the face of uncertainty and despair.