Science fiction, whose roots go back to ancient times, is related to fantasy, horror, and superhero fiction, and contains many subgenres. Its exact definition has long been disputed among authors, critics, scholars, and readers.
Science fiction literature, film, television, and other media have become popular and influential over much of the world. Besides providing entertainment, it can also criticize present-day society, and is often said to inspire a "sense of wonder". Prevalent elements include robots, extraterrestrials, space travel, outer space, and futuristic technology.
