Science fiction (sometimes shortened to sci-fi or SF) is a genre of speculative fiction which typically deals with imaginative and futuristic concepts such as advanced science and technology, space exploration, time travel, parallel universes, extraterrestrial life, sentient artificial intelligence, cybernetics, certain forms of immortality (like mind uploading), and the singularity. It has been called the "literature of ideas", and it often explores the potential consequences of scientific, social, and technological innovations.
Science fiction can trace its roots back to ancient mythology, and 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, in literature, film, television, and other media, has become popular and influential over much of the world, and it is also often said to inspire a "sense of wonder". Besides providing entertainment, it can also criticize present-day society and explore alternatives.