Science fiction (abbreviated SF or sci-fi with varying punctuation and capitalization) is a broad genre of fiction that often involves speculations based on current or future science or technology. Science fiction is found in books, art, television, films, games, theatre, and other media. In organizational or marketing contexts, science fiction can be synonymous with the broader definition of speculative fiction, encompassing creative works incorporating imaginative elements not found in contemporary reality; this includes fantasy, horror, and related genres.

Science fiction differs from fantasy in that, within the context of the story, its imaginary elements are largely possible within scientifically established or scientifically postulated laws of nature (though some elements in a story might still be pure imaginative speculation). Exploring the consequences of such differences is the traditional purpose of science fiction, making it a "literature of ideas".

Science fiction is largely based on writing entertainingly and rationally about alternate possibilities

in settings that are contrary to known reality.

These may include:

*A setting in the future, in alternative time lines, or in a historical past that contradicts known facts of history or the archeological record

*A setting in outer space, on other worlds, or involving aliensSterling, Bruce. "Science fiction" in Encyclopædia Britannica 2008 [http://www.britannica.com/oscar/print?articleId=66289&fullArticle=true&tocId=235716]

*Stories that involve technology or scientific principles that contradict known laws of nature

*Stories that involve discovery or application of new scientific principles, such as time travel or psionics, or new technology, such as nanotechnology, faster-than-light travel or robots, or of new and different political or social systems

Undersea Kingdom (1936) is a Republic Pictures film serial released in response to Universal's Flash Gordon. It was the second of the sixty-six serials made by Republic Pictures.

Following a suspicious earthquake, and detecting a series of signals, Professor Norton leads an expedition, including Lt Crash Corrigan and Reporter Diana Compton, in his Rocket Submarine to the suspected location of Atlantis. Finding the lost continent they become embroiled in an Atlantean civil war between Sharad (with his White Robes) and the usurper Unga Khan (with his Black Robes) who wishes to conquer Atlantis and then destroy the upper world with Earthquakes generated by his Disintegrator. Thus he will rule the world unless he can be stopped in time.

The star of the serial is Ray "Crash" Corrigan, using that screenname for the first time. The name was created to sound similar to "Flash Gordon", in one of many similarities. Formerly a stunt man ? he was the person swinging on vines in Tarzan the Ape Man ? Corrigan went on to use this screenname for the rest of his career in serials and B-Westerns.

The first two chapters of the serial were mocked on the TV show Mystery Science Theater 3000.

Star Wars is an epic space opera franchise initially conceived by George Lucas during the 1970s and significantly expanded since that time. The first film in the franchise was simply titled Category: Star Wars Episode IV - : A New Hope|Star Wars, but later had the subtitle Episode IV A New Hope added to distinguish it from its sequels and prequels. Star Wars was released on May 25, 1977 by 20th Century Fox, and became a worldwide pop culture phenomenon, initially spawning two sequels. Twenty-two years after Star Wars was released, Lucas began the release of a second trilogy as a prequel to the original trilogy.

The franchise has spawned other media including novels, television series, video games, and comic books. These supplements to the film trilogies comprise the Star Wars Expanded Universe, and have resulted in significant development of the series' fictional universe. As of 2008, the overall box office revenue generated by the six Star Wars films has totalled approximately $4.3 billion, making it the third-highest grossing film series.