Existentialism is a way of thinking that focuses on what it means for people to exist. It is a philosophical movement. It became well known in books and movies of the 19th and 20th centuries. Existentialism is known for dealing with nihilistic problems, but is generally still a kind of anti-nihilism. It says that humans have will and consciousness, but they live in a world that does not. The premise that people must make choices about their life while knowing they are mortal is what existentialism is all about.