Science Fiction is a genre of fiction that deals with the extrapolation of current trends in science and technology into either the near or distant future. Works of science fiction can be found in literature, television, film and video games, as well as in many of other forms of media and entertainment.

Science fiction is often grouped together with fantasy, and while it can have fantastical elements, it is notably distinct from the fantasy genre. Fantasy is generally placed in a historic-based (often pseudo-medieval) setting, and the characters' abilities come from magic. While science fiction may sometimes take place in historical settings (for example, William Gibson and Bruce Sterling's The Difference Engine, which posits that Charles Babbage's Difference Engine was completed and led to a computer revolution during the Victorian era), it is usually set in a near or distant future. Even if the abilities characters in science fiction have appear to be magical, they are generally explained by science. There are some works, notably Marion Zimmer Bradley's Darkover series, that straddle the line between fantasy and science fiction.

'Hard' science fiction extrapolates technological advancements from the current state of science, and sticks to currently-approved theories accepted within the science communities to not be decried fantasy. Alternate history (which rarely has anything to do with science fiction other than the means to create the changes, but it serves a similar fanbase) imagines what would have happened if certain historic events had or had not taken place (for example, if the Axis powers had won World War II, Abraham Lincoln had not been assassinated, or George Washington had had a dirigible at his disposal). Time travel fiction sends its characters back in time, sometimes creating an alternate history situation. Space opera uses the trappings and settings of science fiction as a backdrop for a dramatic (or, at times, humorous) story, and often only makes a nod to actual science. Cyberpunk deals with advances in computer science, often in an urban setting, while post-apocalyptic fiction imagines what human society or the Earth would be like after a catastrophic disaster struck.