Jean-Paul Sartre was an influential writer who explored themes of existentialism in depth through his literary works, including "Being and Nothingness." His philosophy emphasized the importance of individual freedom and choice, arguing that humans are condemned to create their own essence in a seemingly indifferent universe. Sartre's insights into the nature of existence, responsibility, and authenticity significantly shaped modern thought, influencing literature, philosophy, and psychology. His works invite deep reflection on the human condition and challenge readers to confront the complexities of life and the quest for meaning.