Movies have evolved from their early beginnings to become a major part of society. Society influences the types of movies that are popular, as filmmakers create movies on themes that will attract wide audiences. For example, during times of war society demanded war movies, and after innovations like sound films and CGI, musicals and science fiction became popular. Movies also influence society by conveying life lessons and perspectives that shape viewers' morals and worldviews. They can be used for propaganda to educate populations or spread government ideals. The relationship between movies and society is reciprocal, as they continually impact one another over time.