Steampunk is a subgenre of speculative fiction, usually set in an anachronistic Victorian or quasi-Victorian alternate history setting. It could be described by the slogan "What the past would look like if the future had happened sooner." It includes fiction with science fiction, fantasy or horror themes.
The origin of the term "steampunk" was originally as a tongue in cheek variant of "cyberpunk": rather than emphasising the dystopia computer, robotic, and nanotechnology focus of cyberpunk fiction, steampunk fiction focuses more intently on real, theoretical or cinematic Victorian-era technology, including steam engines, clockworks, and difference engines. While much of steampunk can be found in Victorian-era settings, it doesn't necessarily have to be, and has expanded into medieval settings, the fantasy genre, and many others.
Originally, like cyberpunk, steampunk was typically dystopian, often with noir and pulp fiction themes, as it was a variant of Cyberpunk. As the genre developed, it came to adopt more of the broadly appealing utopian sensibilities of Victorian Scientific Romances. Various secret societies and conspiracy theories are often featured, and some steampunk includes significant fantasy elements. There are frequently Lovecraftian, occult and Gothic horror influences as well.
Types of steampunk
Although originally concieved as being Victorian-era science fiction only, the term has become common use for many related forms of speculative fiction set in the pre-Electric age era. Sub-genres include:
Any pre-electricty science fiction work with an emphasis on steam- or spring-propelled gadgets. This also includes many alternative history stories in the genre. This category, itself, has sub-genres:
- Classic Steampunk: Science fiction written during the Victorian era, including some of the works by Jules Verne, H.G. Wells and Mark Twain.
- Medieval Steampunk: Speculative fiction set during the Middle Ages.
- Victorian Steampunk: A modern Science Fiction work (post-1930s) that is set in the early parts of the industrial revolution.
- Western Steampunk: Science fiction set in the American Old West.
Since the late 1990s the application of the steampunk label has expanded out of the pure science fiction realm into other forms of speculative fiction, including both steampunk science fiction alongside traditional fantasy or horror elements. Fantasy steampunk is any work of fantasy fiction that combines magic with steam- or spring-powered gadget technology.
Though there are precedents as old as Jules Verne and H. G. Wells, in the Scientific Romances, Voyages Extraordinaires and Edisonade s of the Victorian and Edwardian eras, Steampunk as a genre developed in the 1980s as an offshoot of, or reaction to, Cyberpunk.
William Gibson and Bruce Sterling's 1992 novel The Difference Engine is often credited with inspiring the term "Steampunk". This novel applies the principles of Gibson and Sterling's Cyberpunk writings to an alternate Victorian era where Charles Babbage's mechanical computer was actually built. However, the earliest citation for the term belongs to Jeter. 
Some cite the origin of the Steampunk concept going back as far as Walt Disney's 1954 adaptation of Verne's 20,000 Leagues Under the Sea. The film was a benchmark in its conscious choice to maintain a Victorian look and feel rather than updating the story (as was the case with the 1953 adaptation of Wells' The War of the Worlds).
The present and growing popularity of Steampunk is likely due in large part to Alan Moore and Kevin O'Neill's two League of Extraordinary Gentlemen comic series. Moore's concept and writing made the series popular, but reviews attaching the term "Steampunk" to it became many peoples' first exposure to the term.
There are two main themes within Steampunk: "Historical Steampunk" and "Fantasy Steampunk".  Historical Steampunk tends to be more science fiction-oriented: presenting an alternate history, presenting real locales and persons from history with different technology. Fantasy Steampunk, on the other hand, tends to present steampunk in a completely imaginary fantasy world, often populated by fantastic creatures coexisting with steampunk technology.
The most common Historical Steampunk settings are the Victorian and Edwardian eras, though some in this "Victorian Steampunk" category can go as early as the Industrial Revolution. Some examples of this type include the comic League of Extraordinary Gentlemen, the novel The Difference Engine and the Dinotopia book series. The next most common setting is "Western Steampunk", being a science fictionalized American Western, as seen in the television shows The Wild Wild West and The Adventures of Brisco County, Jr. and films Wild Wild West and Back to the Future Part III.
As a continuing play on the cyber/steam-punk naming convention, there have been a handful of novels published, self-described as "sandal-punk" which posit a world in which ancient civilization never collapsed into the Dark Ages and instead saw rapid technological advancement after a few key discoveries are made or developed into industrial technologies (eg: Hero of Alexandria's steam engine, built around 130 BC). There are also Historical Steampunk stories set in the Middle Ages, in which steam and industrial technology is developed in or brought to the Mediaeval era (thus dubbed "Mediaeval Steampunk"). Mark Twain's novel A Connecticut Yankee in King Arthur's Court is a good example of this type.
Some examples of Fantasy Steampunk include the Castle Falkenstein role-playing game, The Vision of Escaflowne anime series, and many of the games in the Final Fantasy role-playing game series. In between Historical and Fantasy Steampunk is a type which takes place in a hypothetical future or a fantasy equivalent of our future where some variety of Steampunk-style technology and aesthetics dominate. Examples include the Neotopia comic and even Disney's Treasure Planet film. This could also be considered a type of Retro-futurism.
Steampunk as a culture
The most immediate form of Steampunk culture is the community of fans surrounding the genre. Others move beyond this, attempting to adopt a "Steampunk" aesthetic through fashion, home decor and even music. This movement may also be (more accurately) described as "Neo-Victorianism", which is the amalgamation of Victorian aesthetic principles with modern sensibilities and technologies.
"Steampunk" fashion has no set guidelines, but tends towards solving the hypothetical questions of "what if Punks, Goths and Rivets lived in the Victorian era?" This may include Mohawks and extensive peircings with corsets and tattered petticoats, Victorian suits with goggles and boots with large soles and buckles or straps, and the Elegant Gothic Lolita and Elegant Gothic Aristocrat styles.
"Steampunk" music is even less defined, and tends to apply to any modern musicians whose music evokes a feeling of the Victorian era or Steampunk. This may include such diverse artists as Rasputina, Thomas Dolby, Paul Roland and Sarah Brightman.
- The Steampunk Trilogy by Paul Di Filippo
- The Difference Engine by William Gibson & Bruce Sterling -- the designs of Charles Babbage led to the wide usage of mechanical computers in Victorian England. (See difference engine)
- Morlock Night by K. W. Jeter
- The Light Ages by Ian R. MacLeod
- The Grand Ellipse by Paula Volsky
- Pasquale's Angel by Paul McAuley
- Jack Faust by Michael Swanwick
- Perdido Street Station by China Miéville
- Age of Unreason Trilogy by Gregory Keyes
- by Mike Pondsmith
- A Nomad of the Time Streams by Michael Moorcock
- Infernal Devices by K. W. Jeter
- The Sundowners Series by James Swallow
- Homunculus by James Blaylock
- L'équilibre des paradoxes by Michel Pagel
- Lord Kelvin's Machine by James Blaylock
- Anti-Ice by Stephen Baxter
- Greatwinter trilogy, by Sean McMullen
- The Anubis Gates by Tim Powers
- Dinotopia: A Land Apart from Time and The World Beneath by James Gurney
Quasi-Victorian science fiction
- A Transatlantic Tunnel, Hurrah! by Harry Harrison -- an alternate history novel written and set in the 1970s in a world where the American Revolution failed and the British Empire is still going strong. It has a nice mix of technologies advanced or behind ours, with high powered lasers used for drilling, while Babbage engines are used to do calculations for sub-orbital flights.
- Queen Victoria's Bomb by Ronald Clark -- in the mid 19th century; a physicist gets the idea of isotopic separation after seeing pebbles graded by size on a pebble beach, and makes an atomic bomb. He intends to use it to end the Crimean War, but it never gets used, and no difference is made to history.
- The Diamond Age by Neal Stephenson -- A cyberpunk adventure in a nanotechnological future, with much of the action in a neo-Victorian society
- The Peshawar Lancers by S.M. Stirling -- Meteors devastate Europe and America in the 19th century, causing much of the British upper class to flee to India. The story is set in 2025 in a thoroughly Indianized Angrezi Raj (British Empire), with its capital in Delhi.
- From the Earth to the Moon by Jules Verne
- 20,000 Leagues Under the Sea by Jules Verne
- The Mysterious Island by Jules Verne
- Around the World in 80 Days by Jules Verne
- Robur the Conqueror by Jules Verne
- Journey to the Center of the Earth by Jules Verne
- The Time Machine by H. G. Wells
- The War of the Worlds by H. G. Wells
- The Island of Dr. Moreau by H. G. Wells
- The Invisible Man by H. G. Wells
- The Ablest Man in the World by Edward Page Mitchell
- The Lost World by Sir Arthur Conan Doyle
- King Solomon's Mines by Sir H. Rider Haggard
- Tarzan of the Apes by Edgar Rice Burroughs
- A Connecticut Yankee in King Arthur's Court by Mark Twain
Comics / graphic novels
- Daisy Kutter by Kazu Kibuishi
- Le Régulateur T1 : Ambrosia by Corbeyran
- Girl Genius by Phil and Kaja Foglio
- The League of Extraordinary Gentlemen 1898 by Alan Moore
- Steam Detectives manga by Kia Asamiya
- Steampunk by Joe Kelly and Chris Bachalo
- Texas Steampunk series by Lea Hernandez : Cathedral Child and Clockwork Angels
- Les Cités Obscures by Benoît Peeters and François Schuiten
- (DC Comics Elseworlds) by Brian Augustyn and Mike Mignola and (DC Comics Elseworlds) by Augusten and Eduardo Barreto
- (DC Comics Elseworlds) by Adisakdi Tantimedh and Galen Showman
- Justice Riders (DC Comics Elseworlds) by Chuck Dixon and J. H. Williams III
- (DC Comics Elseworlds) by Mike Mignola and Troy Nixey
- The Amazing Screw-On Head by Mike Mignola
- Neotopia by Rod Espinosa
- The Adventures of Luther Arkwright and Heart of Empire, or The Legacy of Luther Arkwright by Bryan Talbot
- Hellsing by Kouta Hirano
Steampunk role-playing game material
- Castle Falkenstein (RPG) by Mike Pondsmith
- GURPS Steampunk by William H. Stoddard
- Iron Kingdoms by Privateer Press
- Sorcery & Steam by Fantasy Flight Games
- Space: 1889
- Forgotten Futures
- Brassy's Men by Interactivities Ink (Live action roleplaying game)
- Steam Trek online RPG group 
- A Trip to the Moon (1902)
- The Impossible Voyage (1904)
- Conquest of the Pole (1912)
- The Invisible Man (1933)
- Bride of Frankenstein (1935)
- 20,000 Leagues Under the Sea (1954)
- The Fabulous World of Jules Verne (1958)
- Journey to the Center of the Earth (1959)
- The Time Machine (1960, 2002)
- Master of the World (1961)
- First Men in the Moon (1964)
- The Asphyx (1972)
- The Adventures of Mark Twain (1982 claymation)
- Greystoke, the Legend of Tarzan (1983)
- Back to the Future Part III (1990)
- Bram Stoker's Dracula (1994)
- Mary Shelley's Frankenstein (1994)
- The City of Lost Children (1995)
- Casper (1995)
- Wild Wild West (1998)
- Sleepy Hollow (1999)
- Atlantis: The Lost Empire (2001)
- The League of Extraordinary Gentlemen (2003)
- Steamboy (2004 anime)
- Van Helsing (2004)
- Hellboy (2004)
- Around the World in 80 Days (2004)
- The Adventures of Brisco County, Jr., FOX series
- Doctor Who: "Pyramids of Mars" (1975), "The Talons of Weng-Chiang" (1977), "Ghost Light" (1989)
- Fullmetal Alchemist, anime TV series
- Gormenghast BBC series
- Jack of All Trades, syndicated series
- Last Exile, 2003 26-episode anime TV series
- Legend , series
- Nadia: The Secret of Blue Water, anime TV series
- Read or Die, short anime series
- Sakura Wars, anime TV series
- The Secret Adventures of Jules Verne, Sci Fi Channel series
- Secret of Cerulean Sand, anime TV series
- Sir Arthur Conan Doyle's The Lost World , syndicated series
- Steam Detectives, anime series
- Trigun, anime series
- The Wild Wild West, ABC series
- The Vision of Escaflowne, anime TV series
- Arcanum: of Steamworks and Magick Obscura
- Final Fantasy
- The Chaos Engine
- Chrono Trigger
- Chrono Cross (aka Chrono Trigger 2)
- Shining Force Series
- Steampunk - Victorian Adventurers in a Past that Wasn't
- History of Robots of the Victorian Era
- Steampunk Central
- Gothic Steam Phantastic