->''"It's been said that science fiction and fantasy are two different things: science fiction the improbable made possible; fantasy, the impossible made probable..."''
-->-- '''Creaor/RodSerling''', ''Series/TheTwilightZone1959''
%% One quote. Please place additional entries on the quotes tab.

As a literary genre, Science Fiction (a subset of SpeculativeFiction) is broad and incorporates subgenres ranging from SteamPunk to CyberPunk, running headalong through SpaceOpera on the way.

Science Fiction depends on asking "what if?" (Not quite the same thing as WhatIf). Or as an obscure 1930s Science Fiction musical asked, "just imagine"...

* ...[[FasterThanLightTravel travel between stars]] were possible.
* ...[[FirstContact aliens came]] to Earth.
* ...a {{utopia}} or a {{dystopia}}.
* ...we had [[StockSuperpowers superhuman abilities]].
* [[AlternateHistory ...a war had favored the other side.]]
* [[ItsAWonderfulPlot ...you could visit a world where you were never born.]]

The one defining(-ish, definitions differ) trait of Science Fiction is that there is technology that doesn't exist ''in the time period the story is written in''. Consider ''[[Literature/TwentyThousandLeaguesUnderTheSea 20,000 Leagues Under the Sea]]''. The story was written in a time when submarines were still at the prototype stage, so ''20,000 Leagues Under the Sea'' falls within the boundaries of Science Fiction.

However, Science Fiction is as much a genre as a [[StandardSciFiSetting setting.]] Often, the technology is a means to explore a concept, and the story could be a detective story focusing on how advanced technology affects crime and policing. This story would be both Science Fiction and DetectiveStory.

In general, without getting too much into the advanced and diverse subgenres of science fiction, there are two schools -- [[MohsScaleofSciFiHardness "hard" and "soft"]]. While the distinction isn't always clear cut, there are a few key differences. Hard science fiction relies on using already established science or justifying its fictionalized science using carefully calculated predictions. Hard SF tries to use the advanced technology as something that is important in itself, with its consequences, limitations and new uses being the main plot points. Due to the heavy focus on the scientific aspect, this is a rather niche market. Soft science fiction includes everything else, and generally falls under two major schools - adventure/pulp science fiction (which includes the SpaceOpera) and social science fiction. The former uses technology as a means to an end, merely a backdrop that allows TheCaptain to fight for Justice™ with a [[StunGun Stun Ray]] against the evil aliens and have [[BoldlyComing space sex]] with the GreenSkinnedSpaceBabe, instead of having to have him use a boring, ordinary gun and have boring, ordinary sex, with the boring, ordinary-skinned Earth babe. In the latter, the technology is used as a means of exploring characters and its social/psychological effects. Of course, it is entirely possible to have an action packed adventure story with deep social commentary. In both schools of soft science fiction, it usually doesn't matter whether the technology used is actually plausible or not, and there is often little to no explanation as to how the technology would actually work. Otherwise, it may rely on such devices as TechnoBabble to maintain a "sci-fi" atmosphere without the author actually having to use detailed scientific principles. Because hard science fiction tends to focus more on scientific detail and soft science fiction focuses on well developed characters and/or adventure, there is a divide between certain sections of the fandom. This divide has been around since, essentially, [[http://www.harkavagrant.com/index.php?id=231 the very beginning of the genre]]. However, "hard" and "soft" say nothing about quality or literary value, just the level of scientific detail and accuracy used.

As with everything, there is often a [[MohsScaleOfSciFiHardness blend of Hard and Soft]] science fiction. It is perfectly possible to write a hard Science Fiction story about TheCaptain running around shooting people with miniaturized microwave emitters designed to incapacitate people without killing them, shooting aliens and having sex with {{Green Skinned Space Babe}}s (with no chance of conception because green aliens are biologically incompatible with humans), just as one can go into considerable detail justifying otherwise implausible technology that is [[ClarkesThirdLaw much like magic]] (usually accomplished by deliberately altering basic scientific laws) and its effects on scientific research. This can often lead to HiddenDepths.

Science Fiction authors and fans are [[BerserkButton notoriously cranky]] about [[SciFiGhetto how their work is not taken seriously by the literary community]], and especially resent being lumped in with [[{{Fantasy}} the fantasy genre.]] (SpeculativeFiction, an umbrella term for all varieties of imaginative literature, has an analysis page that explains the [[Analysis/SpeculativeFiction differences between Fantasy and Science Fiction]].) Note also that many Science Fiction fans dislike the term SciFi: to them it suggests the [[{{Flanderization}} flanderized]] conception of the genre in popular culture, with green-skinned aliens, giant space battles and hammy production values. Therefore, [[InsistentTerminology they will insist on calling it]] [[SpellMyNameWithAnS SF]] for short.

See also: SpeculativeFictionTropes, SpeculativeFictionSeries, SpeculativeFictionCreatorIndex, TechnologyMarchesOn.

+ ScienceFictionAnimatedFilms
+ ScienceFictionAnimeAndManga
+ ScienceFictionComicBooks
+ ScienceFictionFanFic
+ ScienceFictionFilms
+ ScienceFictionLiterature
+ ScienceFictionPodcasts
+ ScienceFictionSeries
+ ScienceFictionTabletopGames
+ ScienceFictionVideoGames
+ ScienceFictionVisualNovels
+ ScienceFictionWebOriginals
+ SciFiWebcomics
+ ScienceFictionWesternAnimation

(Exact definitions of these genres, including whether they're really Sci-Fi, and how much they overlap with Fantasy, will vary from person to person.)
* [[MohsScaleOfScienceFictionHardness Hard and Soft Science Fiction]]
* AlienInvasion
* [[AfterTheEnd Apocalyptic and Post-Apocalyptic Fiction]]
* MechaShow
** RealRobotGenre
** SuperRobotGenre
* MilitaryScienceFiction
* NewWaveScienceFiction
* NewWeird
* PlanetaryRomance
* PunkPunk
** {{Cyberpunk}}
** {{Steampunk}}
* SciFiHorror
* ScienceFantasy
* SpaceOpera
* SpaceWestern
* TeslaTechTimeline
* TimeTravel
* TranshumansInSpace