Science fiction (often shortened to SF or sci-fi) is a genre of speculative fiction, typically dealing with imaginative concepts such as futuristic science and technology, space travel, time travel, faster than light travel, parallel universes, and extraterrestrial life. Science fiction often explores the potential consequences of scientific and other innovations, and has been called a "literature of ideas". It usually avoids the supernatural, and unlike the related genre of fantasy, historically, science-fiction stories were intended to have a grounding in science-based fact or theory at the time the story was created, but this connection is now limited to hard science fiction.
