Science Fiction is a fairly vague form of fiction that usually entails the speculative use of future sciences upon characters. Books such as Neil Stephenson's Snowcrash and Robert A. Heinlein's Red Planet are typical examples of science fiction. It is often abbreviated as sci-fi or SF.
The genre is popular with makers of TV shows and movies. Star Wars and Star Trek are probably the most famous science fiction products around, both having millions of devoted fans.