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:
Science fiction is difficult to define, as it includes a wide range of subgenres and themes. Author and editor Damon Knight summed up the difficulty by stating that "science fiction is what we point to when we say it", a definition echoed by author Mark C. Glassy, who argues that the definition of science fiction is like the definition of pornography: you don't know what it is, but you know it when you see it. Vladimir Nabokov argued that if we were rigorous with our definitions, Shakespeare's play The Tempest would have to be termed science fiction.
According to science fiction writer Robert A. Heinlein, "a handy short definition of almost all science fiction might read: realistic speculation about possible future events, based solidly on adequate knowledge of the real world, past and present, and on a thorough understanding of the nature and significance of the scientific method." Rod Serling's definition is "fantasy is the impossible made probable. Science Fiction is the improbable made possible." Lester Del Rey wrote, "Even the devoted aficionado– or fan- has a hard time trying to explain what science fiction is", and that the reason for there not being a "full satisfactory definition" is that "there are no easily delineated limits to science fiction."
Forrest J. Ackerman used the term "sci-fi" at UCLA in 1954. As science fiction entered popular culture, writers and fans active in the field came to associate the term with low-budget, low-tech "B-movies" and with low-quality pulp science fiction.   By the 1970s, critics within the field such as Terry Carr and Damon Knight were using "sci-fi" to distinguish hack-work from serious science fiction, and around 1978, Susan Wood and others introduced the pronunciation "skiffy". Peter Nicholls writes that "SF" (or "sf") is "the preferred abbreviation within the community of sf writers and readers". David Langford's monthly fanzine Ansible includes a regular section "As Others See Us" which offers numerous examples of "sci-fi" being used in a pejorative sense by people outside the genre.
As a means of understanding the world through speculation and storytelling, science fiction has antecedents back to mythology, though precursors to science fiction as literature can be seen in Lucian's True History in the 2nd century,     some of the Arabian Nights tales, The Tale of the Bamboo Cutter in the 10th century, Ibn al-Nafis' Theologus Autodidactus in the 13th century, and Cyrano de Bergerac' Voyage de la Terre à la Lune and Des états de la Lune et du Soleil in the 17th century. Following the Age of Reason and the development of modern science itself, Voltaire's Micromégas was one of the first true science fiction works, together with Jonathan Swift's Gulliver's Travels. and Kepler's Somnium. This latter work is considered, by Carl Sagan and Isaac Asimov, to be the first science fiction story. It depicts a travel to the Moon and how the Earth movement is seen from there.
Following the 18th century development of the novel as a literary form, in the early 19th century, Mary Shelley's books Frankenstein and The Last Man helped define the form of the science fiction novel; later Edgar Allan Poe wrote a story about a flight to the moon. More examples appeared throughout the 19th century. Then with the dawn of new technologies such as electricity, the telegraph, and new forms of powered transportation, writers like Jules Verne and H. G. Wells created a body of work that became popular across broad cross-sections of society. In the late 19th century the term "scientific romance" was used in Britain to describe much of this fiction. This produced additional offshoots, such as the 1884 novella Flatland: A Romance of Many Dimensions by Edwin Abbott Abbott. The term would continue to be used into the early 20th century for writers such as Olaf Stapledon.
In the early 20th century, pulp magazines helped develop a new generation of mainly American SF writers, influenced by Hugo Gernsback, the founder of Amazing Stories magazine. In the late 1930s, John W. Campbell became editor of Astounding Science Fiction, and a critical mass of new writers emerged in New York City in a group called the Futurians, including Isaac Asimov, Damon Knight, Donald A. Wollheim, Frederik Pohl, James Blish, Judith Merril, and others. Other important writers during this period included Robert A. Heinlein, Arthur C. Clarke, A. E. van Vogt and Stanisław Lem. Campbell's tenure at Astounding is considered to be the beginning of the Golden Age of science fiction, characterized by hard SF stories celebrating scientific achievement and progress. This lasted until postwar technological advances, new magazines like Galaxy under Pohl as editor, and a new generation of writers began writing stories outside the Campbell mode.
In the 1950s, the Beat generation included speculative writers like William S. Burroughs. In the 1960s and early 1970s, writers like Frank Herbert, Samuel R. Delany, Roger Zelazny, and Harlan Ellison explored new trends, ideas, and writing styles, while a group of writers, mainly in Britain, became known as the New Wave. In the 1970s, writers like Larry Niven and Poul Anderson began to redefine hard SF. Ursula K. Le Guin and others pioneered soft science fiction.
In the 1980s, cyberpunk authors like William Gibson turned away from the traditional optimism and support for progress of traditional science fiction. Star Wars helped spark a new interest in space opera, focusing more on story and character than on scientific accuracy. C. J. Cherryh's detailed explorations of alien life and complex scientific challenges influenced a generation of writers. Emerging themes in the 1990s included environmental issues, the implications of the global Internet and the expanding information universe, questions about biotechnology and nanotechnology, as well as a post-Cold War interest in post-scarcity societies; Neal Stephenson's The Diamond Age comprehensively explores these themes. Lois McMaster Bujold's Vorkosigan novels brought the character-driven story back into prominence. The television series began a torrent of new SF shows, of which Babylon 5 was among the most highly acclaimed in the decade.  Concern about the rapid pace of technological change crystallized around the concept of the technological singularity, popularized by Vernor Vinge's novel Marooned in Realtime and then taken up by other authors.
While SF has provided criticism of developing and future technologies, it also produces innovation and new technology. The discussion of this topic has occurred more in literary and sociological than in scientific forums. Cinema and media theorist Vivian Sobchack examines the dialogue between science fiction film and the technological imagination. Technology does impact how artists portray their fictionalized subjects, but the fictional world gives back to science by broadening imagination. While more prevalent in the beginning years of science fiction with writers like Isaac Asimov, Robert A. Heinlein, Frank Walker and Arthur C. Clarke, new authors like Michael Crichton still find ways to make the currently impossible technologies seem so close to being realized. This has also been documented in the field of nanotechnology with University of Ottawa Professor José Lopez's article "Bridging the Gaps: Science Fiction in Nanotechnology". Lopez links both theoretical premises of science fiction worlds and the operation of nanotechnologies.
Authors and filmmakers draw on a wide spectrum of ideas, but marketing departments and literary critics tend to separate such literary and cinematic works into different categories, or "genres", and subgenres. These are not simple pigeonholes; works can be overlapped into two or more commonly-defined genres, while others are beyond the generic boundaries, either outside or between categories, and the categories and genres used by mass markets and literary criticism differ considerably.
See main article: Hard science fiction. Hard science fiction, or "hard SF", is characterized by rigorous attention to accurate detail in quantitative sciences, especially physics, astrophysics, and chemistry, or on accurately depicting worlds that more advanced technology may make possible. Many accurate predictions of the future come from the hard science fiction subgenre, but numerous inaccurate predictions have emerged as well. For example, Arthur C. Clarke accurately predicted geostationary communications satellites, but erred in his prediction of deep layers of moondust in lunar craters. Some hard SF authors have distinguished themselves as working scientists, including Neal Asher, Adam Roberts, Peter F. Hamilton, Alastair Reynolds, Robert Forward, Gregory Benford, Charles Sheffield, Isaac Asimov, Catherine Asaro, and Geoffrey A. Landis,, while mathematician authors include Rudy Rucker and Vernor Vinge. Other noteworthy hard SF authors include Hal Clement, Larry Niven, Robert J. Sawyer, and Stephen Baxter.
See also: Soft science fiction and Social science fiction. The description "soft" science fiction may describe works based on social sciences such as psychology, economics, political science, sociology, and anthropology. Noteworthy writers in this category include Ursula K. Le Guin and Philip K. Dick.  The term can describe stories focused primarily on character and emotion; SFWA Grand Master Ray Bradbury is an acknowledged master of this art. Some writers blur the boundary between hard and soft science fiction.
Related to Social SF and Soft SF are the speculative fiction branches of utopian or dystopian stories; The Handmaid's Tale, Nineteen Eighty-Four, and Brave New World are examples. Satirical novels with fantastic settings such as Gulliver's Travels may be considered speculative fiction.
See also: Cyberpunk. The Cyberpunk genre emerged in the early 1980s; the name is a portmanteau of "cybernetics" and "punk", and was first coined by author Bruce Bethke in his 1980 short story "Cyberpunk". The time frame is usually near-future and the settings are often dystopian. Common themes in cyberpunk include advances in information technology and especially the Internet (visually abstracted as cyberspace), artificial intelligence and prosthetics and post-democratic societal control where corporations have more influence than governments. Nihilism, post-modernism, and film noir techniques are common elements, and the protagonists may be disaffected or reluctant anti-heroes. Noteworthy authors in this genre are William Gibson, Bruce Sterling, Alfred Bester, Pat Cadigan. James O'Ehley has called the 1982 film Blade Runner a definitive example of the cyberpunk visual style.
See also: Time travel in fiction.
Time travel stories have antecedents in the 18th and 19th centuries, and this subgenre was popularized by H. G. Wells's novel The Time Machine. Stories of this type are complicated by logical problems such as the grandfather paradox. Time travel is a popular subject in novels, and in television series, either as individual episodes within more general science fiction series, for example, "The City on the Edge of Forever" in Star Trek, or as one-off productions such as The Flipside of Dominick Hide.
See also: Alternate history.
Alternate history stories are based on the premise that historical events might have turned out differently. These stories may use time travel to change the past, or may simply set a story in a universe with a different history from our own. Classics in the genre include Bring the Jubilee by Ward Moore, in which the South wins the American Civil War and The Man in the High Castle, by Philip K. Dick, in which Germany and Japan win World War II. The Sidewise Award acknowledges the best works in this subgenre; the name is taken from Murray Leinster's early story Sidewise in Time. Harry Turtledove is one of the most prominent authors in the subgenre and is often called the "master of alternate history". 
See also: Military science fiction.
Military science fiction is set in the context of conflict between national, interplanetary, or interstellar armed forces; the primary viewpoint characters are usually soldiers. Stories include detail about military technology, procedure, ritual, and history; military stories may use parallels with historical conflicts. Heinlein's Starship Troopers is an early example, along with the Dorsai novels of Gordon Dickson. Joe Haldeman's The Forever War is a critique of the genre, a Vietnam-era response to the World War II-style stories of earlier authors. Prominent military SF authors include David Drake, David Weber, and S. M. Stirling. Baen Books is known for cultivating military science fiction authors.
See also: Superhuman.
Superhuman stories deal with the emergence of humans who have abilities beyond the norm. This can stem either from natural causes such as in Olaf Stapledon's novel Odd John, or be the result of intentional augmentation such as in A.E. Van Vogt's novel Slan. These stories usually focus on the alienation that these beings feel as well as society's reaction to them. These stories have played a role in the real life discussion of human enhancement.
See also: Apocalyptic and post-apocalyptic fiction.
Apocalyptic fiction is concerned with the end of civilization through nuclear war, plague, or some other general disaster or with a world or civilization after such a disaster. Typical of the genre are George R. Stewart's novel Earth Abides and Pat Frank's novel Alas, Babylon. Apocalyptic fiction generally concerns the disaster itself and the direct aftermath, while post-apocalyptic can deal with anything from the near aftermath (as in Cormac McCarthy's The Road) to hundreds or thousands of years in the future, such as in Russell Hoban's novel Riddley Walker and in George Orwell's classic book, Nineteen Eighty-Four
See also: Space Opera.
Space opera emphasizes romantic, often melodramatic adventure, set mainly or entirely in space, generally involving conflict between opponents possessing powerful (and sometimes quite fanciful) technologies and abilities. Perhaps the most significant trait of space opera is that settings, characters, battles, powers, and themes tend to be very large-scale. These stories typically follow the Homeric tradition, in which a small band of adventurers are cast against larger-than-life backdrops of powerful warring factions. Alastair Reynolds' Revelation Space series and the immensely popular Star Wars trilogies are examples of this genre.
See also: Space Western.
Space Westerns could be considered a sub-genre of Space Opera that transposes themes of the American Western books and film to a backdrop of futuristic space frontiers. These stories typically involve "frontier" colony worlds (colonies that have only recently been terraformed and/or settled) serving as stand-ins for the backdrop of lawlessness and economic expansion that were predominate in the American west such as Firefly (TV series) by Joss Whedon and the accompanying movie Serenity (film).
The broader category of speculative fiction includes science fiction, fantasy, alternate histories (which may have no particular scientific or futuristic component), and even literary stories that contain fantastic elements, such as the work of Jorge Luis Borges or John Barth. For some editors, magic realism is considered to be within the broad definition of speculative fiction.
See main article: Fantasy. Fantasy is closely associated with science fiction, and many writers have worked in both genres, while writers such as Anne McCaffrey and Marion Zimmer Bradley have written works that appear to blur the boundary between the two related genres. The authors' professional organization is called the Science Fiction and Fantasy Writers of America (SFWA). SF conventions routinely have programming on fantasy topics,   and fantasy authors such as J. K. Rowling have won the highest honor within the science fiction field, the Hugo Award. Some works show how difficult it is to draw clear boundaries between subgenres; however authors and readers often make a distinction between fantasy and SF. In general, science fiction is the literature of things that might someday be possible, and fantasy is the literature of things that are inherently impossible. Magic and mythology are popular themes in fantasy. Some narratives are described as being essentially science fiction but "with fantasy elements". The term "science fantasy" is sometimes used to describe such material.
See main article: Horror fiction. Horror fiction is the literature of the unnatural and supernatural, with the aim of unsettling or frightening the reader, sometimes with graphic violence. Historically it has also been known as weird fiction. Although horror is not per se a branch of science fiction, many works of horror literature incorporates science fictional elements. One of the defining classical works of horror, Mary Shelley's novel Frankenstein, is the first fully-realized work of science fiction, where the manufacture of the monster is given a rigorous science-fictional grounding. The works of Edgar Allan Poe also helped define both the science fiction and the horror genres. Today horror is one of the most popular categories of films.
See main article: Mystery fiction. Works in which science and technology are a dominant theme, but based on current reality, may be considered mainstream fiction. Much of the thriller genre would be included, such as the novels of Tom Clancy or Michael Crichton, or the James Bond films. Modernist works from writers like Kurt Vonnegut, Philip K. Dick, and Stanisław Lem have focused on speculative or existential perspectives on contemporary reality and are on the borderline between SF and the mainstream. According to Robert J. Sawyer, "Science fiction and mystery have a great deal in common. Both prize the intellectual process of puzzle solving, and both require stories to be plausible and hinge on the way things really do work." Isaac Asimov, Walter Mosley, and other writers incorporate mystery elements in their science fiction, and vice versa.
See main article: Superhero fiction. Superhero fiction is a genre characterized by beings with much higher than usual capability and prowess, generally with a desire or need to help the citizens of their chosen country or world by using his or her powers to defeat natural or superpowered threats. Many superhero fiction characters involve themselves (either intentionally or accidentally) with science fiction and fact, including advanced technologies, alien worlds, time travel, and interdimensional travel; but the standards of scientific plausibility are lower than with actual science fiction. Authors of this genre include Stan Lee (co-creator of Spider-Man, the Fantastic Four, the X-Men, and the Hulk); Marv Wolfman, the creator of Blade for Marvel Comics, and The New Teen Titans for DC Comics; Dean Wesley Smith (Star Trek, Smallville, Spider-Man, and X-Men novels) and Superman writers Roger Stern and Elliot S! Maggin.
Science fiction fandom is the "community of the literature of ideas... the culture in which new ideas emerge and grow before being released into society at large". Members of this community, "fans", are in contact with each other at conventions or clubs, through print or online fanzines, or on the Internet using web sites, mailing lists, and other resources.
SF fandom emerged from the letters column in Amazing Stories magazine. Soon fans began writing letters to each other, and then grouping their comments together in informal publications that became known as fanzines. Once they were in regular contact, fans wanted to meet each other, and they organized local clubs. In the 1930s, the first science fiction conventions gathered fans from a wider area. Conventions, clubs, and fanzines were the dominant form of fan activity, or "fanac", for decades, until the Internet facilitated communication among a much larger population of interested people.
Among the most respected awards for science fiction are the Hugo Award, presented by the World Science Fiction Society at Worldcon, and the Nebula Award, presented by SFWA and voted on by the community of authors. One notable award for science fiction films is the Saturn Award. It is presented annually by The Academy of Science Fiction, Fantasy, and Horror Films.
There are national awards, like Canada's Aurora Award, regional awards, like the Endeavour Award presented at Orycon for works from the Pacific Northwest, special interest or subgenre awards like the Chesley Award for art or the World Fantasy Award for fantasy. Magazines may organize reader polls, notably the Locus Award.
Conventions (in fandom, shortened as "cons"), are held in cities around the world, catering to a local, regional, national, or international membership. General-interest conventions cover all aspects of science fiction, while others focus on a particular interest like media fandom, filking, etc. Most are organized by volunteers in non-profit groups, though most media-oriented events are organized by commercial promoters. The convention's activities are called the "program", which may include panel discussions, readings, autograph sessions, costume masquerades, and other events. Activities that occur throughout the convention are not part of the program; these commonly include a dealer's room, art show, and hospitality lounge (or "con suites").
Conventions may host award ceremonies; Worldcons present the Hugo Awards each year. SF societies, referred to as "clubs" except in formal contexts, form a year-round base of activities for science fiction fans. They may be associated with an ongoing science fiction convention, or have regular club meetings, or both. Most groups meet in libraries, schools and universities, community centers, pubs or restaurants, or the homes of individual members. Long-established groups like the New England Science Fiction Association and the Los Angeles Science Fantasy Society have clubhouses for meetings and storage of convention supplies and research materials. The Science Fiction and Fantasy Writers of America (SFWA) was founded by Damon Knight in 1965 as a non-profit organization to serve the community of professional science fiction authors. Fandom has helped incubate related groups, including media fandom, the Society for Creative Anachronism, gaming, filking, and furry fandom.
The first science fiction fanzine, "The Comet", was published in 1930. Fanzine printing methods have changed over the decades, from the hectograph, the mimeograph, and the ditto machine, to modern photocopying. Subscription volumes rarely justify the cost of commercial printing. Modern fanzines are printed on computer printers or at local copy shops, or they may only be sent as email. The best known fanzine (or "'zine") today is Ansible, edited by David Langford, winner of numerous Hugo awards. Other fanzines to win awards in recent years include File 770, Mimosa, and Plokta. Artists working for fanzines have risen to prominence in the field, including Brad W. Foster, Teddy Harvia and Joe Mayhew; the Hugos include a category for Best Fan Artists. The earliest organized fandom online was the SF Lovers community, originally a mailing list in the late 1970s with a text archive file that was updated regularly. In the 1980s, Usenet groups greatly expanded the circle of fans online. In the 1990s, the development of the World-Wide Web exploded the community of online fandom by orders of magnitude, with thousands and then literally millions of web sites devoted to science fiction and related genres for all media. Most such sites are small, ephemeral, and/or very narrowly focused, though sites like SF Site offer a broad range of references and reviews about science fiction.
See also: Fan fiction terminology. Fan fiction, known to aficionados as "fanfic", is non-commercial fiction created by fans in the setting of an established book, film, or television series. This modern meaning of the term should not be confused with the traditional (pre-1970s) meaning of "fan fiction" within the community of fandom, where the term meant original or parody fiction written by fans and published in fanzines, often with members of fandom as characters therein ("faan fiction"). Examples of this would include the Goon stories by Walt Willis. In the last few years, sites have appeared such as Orion's Arm and Galaxiki, which encourage collaborative development of science fiction universes. In some cases, the copyright owners of the books, films, or television series have instructed their lawyers to issue "cease and desist" letters to fans.
The study of science fiction, or science fiction studies, is the critical assessment, interpretation, and discussion of science fiction literature, film, new media, fandom, and fan fiction. Science fiction scholars take science fiction as an object of study in order to better understand it and its relationship to science, technology, politics, and culture-at-large. Science fiction studies has a long history dating back to the turn of the twentieth century, but it was not until later that science fiction studies solidified as a discipline with the publication of the academic journals Extrapolation (1959), Foundation - The International Review of Science Fiction (1972), and Science Fiction Studies (1973), and the establishment of the oldest organizations devoted to the study of science fiction, the Science Fiction Research Association and the Science Fiction Foundation, in 1970. The field has grown considerably since the 1970s with the establishment of more journals, organizations, and conferences with ties to the science fiction scholarship community, and science fiction degree-granting programs such as those offered by the University of Liverpool and Kansas University.
Although perhaps most developed as a genre and community in the US and UK, science fiction is a worldwide phenomenon. Organisations devoted to promoting SF in particular countries and in non-English languages are common, as are country- or language-specific genre awards.
See also: Science Fiction South Africa.
See also: Black science fiction.
See also: Science fiction film of India.
See also: Irish Science Fiction Association.
See also: Turku Science Fiction Society.
Germany and Austria:Current well-known SF authors from Germany are five-time Kurd-Laßwitz-Award winner Andreas Eschbach, whose books The Carpet Makers and Eine Billion Dollar are big successes, and Frank Schätzing, who in his book The Swarm mixes elements of the science thriller with SF elements to an apocalyptic scenario. The most prominent German-speaking author, according to Die Zeit, is Austrian Herbert W. Franke.
A well known science fiction book series in German is Perry Rhodan, which started in 1961. Having sold over one billion copies (in pulp format), it claims to be the most successful science fiction book series ever written worldwide.
Australia: David G. Hartwell noted that while there is perhaps "nothing essentially Australian about Australian science-fiction", many Australian science-fiction (and fantasy and horror) writers are in fact international English language writers, and their work is commonly published worldwide. This is further explainable by the fact that Australian inner market is small (with Australian population being around 21 million), and sales abroad are crucial to most Australian writers.