Edisonade is a subgenre that was named retroactively, and it dates back to the nineteenth century. As the name Edison suggests, they center upon the adventures of some brilliant young inventor. In cinema, H.G. Wells' The Time Machine (George Pal's 1960 and Simon Wells' 2002 versions) fits this model to a T with the main character, Alexander Hartdegen, a genius level young inventor who is obsessed with the discovery of invention and pitied or scorned by the people around him. It goes without saying what his star invention is. The best known literature example would be Victor Appleton's Tom Swift stories.
Environmental subgenre tales focus on the ecosystem, usually but not always our Earth's. Often there is a direct threat, caused by humanity or some outside force. Though this subgenre is based on plausible or potentially real world scenarios, Hollywood often busts out of the fence with exaggerated or ludicrous circumstances. Roland Emmerich's feature film The Day After Tomorrow adapted loosely from Bell and Strieber's book The Coming Global Superstorm is a pretty good example.
Science fiction stories containing a strong element of erotica
Explicit sex might be at the center of the plot, or it plays a vivid role in the character's lives. Norman Spinrad's novel The Void Captain's Tale combines these and other SF elements. In the 60's, the Sex Revolution permeated all media, even sci-fi film got into the act with Barbarella starring Jane Fonda. Set in the 41st century, Barbarella ventures through a series of sexual escapades including a bizarre encounter with a sex machine and seduces an angel.
EXOTIC ECOSYSTEMS SCI-FI
Alien worlds offer tremendous possibilities, yet much SF populates them with familiar humanoids. Robert Reed's novels, such as his The Remarkables, depict truly alien beings and environments; as does Ursula LeGuin's novella "The Word for World is Forest."
James Cameron's newly acclaimed box office king Avatar may have an environment and creatures that somewhat resemble Earth, but it probably fits the subgenre's title Exotic Ecosystems more accurately than any other film with it's neon jungles and floating mountains. Also the planet in the 1972 and 2002 versions of Solaris is certainly alien to our world with a global covering ocean that has the ability of mental thought.
The very discovery of life beyond the Earth
Extraterrestrial Life is a huge subgenre, almost a descriptive category. In many of these tales, or even just its signals or ancient artifacts, has a tremendous impact upon current society. Carl Sagan's novel and movie Contact are excellent examples. Jack McDevitt's novel The Hercules Text is another.
SUB-SET: ALIENS SCI-FI
Other-worldly creatures from outer space or other planets. Possibly the first novel about aliens visiting Earth was "Micromegas", by Voltaire (1750), in which two giants from other worlds come to Earth to humble our primitive mental capacities.
SUB-SET: ALIEN INVASION SCI-FI
Alien Invasion stories are self-explanatory and the target is usually, but not always, our Earth. It is a common theme in science fiction stories and film, in which a technologically-superior extraterrestrial society invades Earth. Either with the intent to replace human life, or to enslave it under a colonial system (as in John Travolta's film Battlefield Earth), or in some cases, to use humans as food.
The classic of this subgenre is H.G. Well's War of the Worlds, which has been presented in radio by Orson Welles' in 1938, the 1951 feature film classic, and Stephen Spielberg's film version. Niven and Pournelle's novel Footfall is a well-thought-out example. The film Independence Day, by Roland Emmerich, has become a cultural milestone.
SUB-SET: ASTROBIOLOGY SCI-FI
Astrobiology centers upon alien life. Not necessarily intelligent or technological beings, but the very presence of life that has evolved beyond our Earth. Many such tales involve finding mysterious life forms on Mars or Europa, or floating in the atmosphere of Jupiter. An oft-quoted example is Arthur C. Clarke's short story "A Meeting With Medusa."
SUB-SET: ASTROSOCIOBIOLOGY SCI-FI
Astrosociobiology is an interstitial subgenre that's both narrow and broad. It focuses on the form and function of alien (non-human) civilizations. There are countless examples. CJ Cherryh's "Chanur" novels explore the psychology of a spacefaring feline race. (Giordano Bruno was burned at the stake for, in part, airing such speculations.)
SUB-SET: FIRST CONTACT / ENCOUNTERS SCI-FI
Explores the initial meeting between humans and aliens or, more broadly, of any sentient race's first encounter with another one. First contact ranges from horrific tales of invasions to stories of benign visitors bearing the secrets of advanced technologies and world peace. This could be an alien arriving here, in space, or a human astronaut reaching, or on another planet. There are hundreds of examples in print and film. A precise example of first contact in cinema is Star Trek's eighth feature film First Contact.
SUB-SET: MICROBIOLOGICAL SCI-FI
Microbiological stories feature tiny life-forms, whether Earthly or alien, as a dominating force. They might cause a disease, or act as a transforming agent, deliberately or not. Greg Bear's novel Blood Music is a good example. Janine Ellen Young's novel The Bridge is another. A film example would be The Andromeda Strain 1971, a group of scientists investigate a deadly new alien virus before it can spread.
A mixed genre of story which contains some science fiction and some fantasy elements
This sub-genre is a merging of the two main genres, sometimes leaning toward the sci-fi side of the fence adding advanced technology in the mix. Not so much explored today, but a regular staple in the 1930's and 1940's. With fairy tale like sub-plots and characters, it would often ignore known laws or scientific theories for the sake of the story. Arthur C. Clarke once said, "any sufficiently advanced technology is indistinguishable from magic."
Flash Gordon, Buster Crabbe's matinee serials of the 30's, stomped all over the laws of physics in telling their fantastical tales containing giant lizard like dragons, shark men, and other bizarre characters and creatures. Literature examples could include Anne McCaffrey's "Pern" novels and Edgar Rice Burroughs' Barsoom novels.
FIRM SCIENCE SCI-FI
Firm Science is a specific definition, which can be applied to many subgenres. It refers to a midway point between 'hard' and 'soft' SF, and the inclusion of technology and /or phenomena that are not too fantastic, but may never be invented. This subgenre could also include characters who are grounded in the real world along with their environment, but a unique element of enhanced physical capabilities or elevated powers of the mind exist.
One feature film that may reside within this category could be Christopher Nolan's Inception, where the story's world mirrors the real world for the most part with the exception that the main character has the ability to probe other's dreams.
FIRST LANDINGS SCI-FI
Originally this meant a journey to the Moon, the only 'obvious' world beyond ours. Jules Verne's novel From the Earth to the Moon, also a Golden Globe and Emmy award winning television miniseries, is not the earliest example (that honor goes to Lucian of Samosata, an ancient Roman author), but it's the best known.
There are numerous 'first to Mars' novels, such as Robert Zubrin's First Landing and other similar stories involving most of the known planets and nearby star systems. After the short-lived Apollo program, this subgenre began to depict a hoped-for return to the moon. (In many cases, by determined private entrepreneurs who outrun a moribund NASA.)
Stories of people conquering new frontiers, leaving our world to colonize a preferable one
Usually told with a "Grass is greener" aspect, only to learn that the same problems face them in the new colony. Similar to hardscrabble miners, crafty independent spacemen ply the asteroid belt in search of resources to send back to civilization. A good example is Peter Hyam's film Outland, which is an homage to High Noon.
There are hundreds of examples in print Alfred Bester's novel The Stars My Destination. In many of such stories they're threatened by an aggressive government or big corpration from Earth. New or cut-off colony planets, left to support themselves, have a distinct frontier aspect. Joss Whedon's popular "Firefly/Serenity" franchise depicts such rough colonies.
GENERATION SHIP SCI-FI
Generation Ship stories are set aboard that type of spacecraft. Often those ships are so large, and the voyage so long, that most or all of its inhabitants consider other worlds to be the stuff of legend. It may travel much slower than light across great distances between stars and must also have extraordinarily reliable systems that would not fail even over long periods of time, or alternately that could be repaired by the ship's inhabitants if they did.
Additionally, the ship would have to be almost entirely self-sustaining so as to provide food, air, and water for everyone on board. Since such a ship might take thousands or tens of thousands of years to reach even nearby stars, the original occupants would die during the journey, leaving their descendants to continue traveling. It is estimated that, in order to assure genetic diversity during a centuries-long trip, any generation starship would require at least 500 inhabitants.
However, this could also be achieved for a much smaller crew through the use of sperm banks or egg banks brought along for the journey. The subgenre was pioneered by J. D. Bernal, with his 1929 novel The World, The Flesh, & The Devil. A popular example is Robert Heinlein's novel Orphans of the Sky. The 2009 film Pandorum helmed by German director Christian Alvart showcased such a ship, The Elysium. This massive craft employed hyper-sleep pods for the occupants to survive the journey.
GOLDEN AGE SCI-FI
A period of the 1940s during which the science fiction genre gained wide public attention and many classic science fiction stories were published. While sci-fi literature might have been plentiful in the 1940s, cinema all but abandoned the genre possibly due to World War II and the box office flops of the late thirties including the British feature film Things to Come.
However there were a hand full of films of the forties that at the very least, had sci-fi elements in their premise including Dr. Renault's Secret, Invisible Agent, The Mysterious Mr. M, Dr. Cyclops, King of the Rocket Men, and more
A subgenre of science fiction that involves gothic conventions
Gothic SF is an interstitial subgenre that slants toward the macabre, and deeply atmospheric settings, but not outright horror. ('Atmospheric' in a literary and cultural, not climatological, sense.) Mary Shelley's Frankenstein is often cited as the first such novel.
Numerous film and television versions of Frankenstein have produced including the 1916 silent film, the most famous of all - Boris Karloff portraying the monster in 1931, and Robert De Niro in the 1994 version. Algis Budry's novel Rogue Moon sets a determined pair against a deadly lunar enigma. In Richard Matheson's novel I Am Legend and its several film versions, a scientist battles plague-spawned vampires. Arthur C. Clarke's short story "A Walk in the Dark" is another example.
A particular emphasis on scientific detail and / or accuracy
Stories based on real science & engineering for the most part, it is driven more by ideas than characterization. Near realistic science and technology are central to the plot. Stories in this broad subgenre depict technology that conforms to actual scientific knowledge and physical laws, or extentions of them that scientists consider plausible. If a story is set on a lunar colony, for example, issues of technology may be of greater concern than a character's personal life.
It usually has a good grasp of the scientific principles involved. The real test of whether a story is 'hard' sci-fi or not is this: remove the technological factor or the science from the plotline. If the plot cannot maintain its integrity without it, then the story is 'hard' sci-fi. If the story remains intact, then it is more likely soft sci-fi. Stories typically contain the inclusion of at least one of the "Hard Sciences" such as Astronomy, Physics, and Chemistry, sciences ruled by mathematics and stringent rules.
Other features may include attention to scientific detail and use of current scientific research. Arguably, certain exceptions include favored 'tropes' such as antigravity and FTL travel. There is a great deal of disagreement among readers and writers over what exactly constitutes an interest in scientific detail. Many hard SF stories focus on the natural sciences and technological developments, but many others leave technology in the background.
Others contend that if the technology is left in the background it is an example of soft science fiction. Another distinction within the genre revolves around portrayals of the human condition. Some authors seek to reflect technical accuracy within an advanced, nearly utopian society in which mankind has attained victory over most human ills.
Others seek to portray the impact of technology on the human race with human defects still firmly in place and sometimes even magnified. Much classic science fiction, including the earlier works of A.C. Clarke, Isaac Asimov, Greg Bear, Larry Niven, and Heinlein, fall into this category. Stanley Kubrick's sci-fi cult classic film 2001: A Space Odyssey adapted from Clarke's The Sentinel, makes an extensive effort to keep the technology as realistic as possible with the exception of the mysterious Black Monolith.
HOLLOW EARTH SCI-FI
A subgenre of science fiction that involves gothic conventions
Hollow Earth tales are just that, set within a putatively hollow (or at least honeycombed) planet Earth. The flagship of this subgenre is Jules Verne's novel Journey to the Center of the Earth, which was adapted to a number of film and television version including the 2009 3D version starring Brendan Fraser. Michael Flynn's novella "Where the Winds Are All Asleep" is a modern homage. A popular variant is the aquatic-cavern-filled planet Naboo in the "Star Wars" franchise.
Sci-fi is more or less just a premise to the prime directive of comedy
Light/humorous science fiction may occur within any of these subgenres, or (often) spoof a subgenre. As with comic fantasy, the type of humor varies from light entertainment to satire. This laugh-out-loud subgenre includes John Sladek's novel Mechasm, Rudy Rucker's novel Master of Space and Time, and many others. Douglas Adams' Hitchhiker's Guide to the Galaxy (also a television series and feature film) is one of the best-known examples of humorous science fiction. Other humorous sci-fi films include Spaceballs, Tim Allen's Galaxy Quest, Back to the Future, and more.
Horror and and science fiction seem to go hand in hand. Horrific SF is closely linked to the 'horror' genre, and while it's often bloody, science is crucial to each premise. In Sharman DiVono's novel Blood Moon, an entire lunar base goes slowly insane.
Most examples of this subgenre are short stories, such as Michael Shea's "The Autopsy," Simon Ings's "The Wedding Party," and Terry Bisson's "Necronauts." Horrific sci-fi in cinema is quite popular with examples too many to mention, but to name a few, there's Species, The Thing, Resident Evil, The Fly, Scanners, The Blob, Lifeforce, Event Horizon, and many, many more. Very few films fit this category as well as Ridley Scott's Alien. This film often appears in both Top Sci-fi and Top Horror Best of Lists.
Hyperspace stories include that extra-dimensional realm as a setting. The pioneering classic of this subgenre is Edward Abbot's 1884 novel Flatland, a Romance of Many Dimensions, although our familiar third spatial axis is the "extra" one. (In a later sequel, Sphereland, by Dionys Burger, a talking hypersphere arrives.)
That realm might play a major role in allowing the characters to travel rapidly between star systems (and/or time periods, etc.), or there might be human dwellings and/or aliens within that arcane realm. A good example is Star Trek: Deep Space Nine, with its mysterious wormhole-dwelling 'prophet' aliens.
Kaiju or Tokusatsu is a Japanese subgenre, long popular in the rest of the world. These epics always feature one or more kaiju, meaning big powerful quirky monsters. A major example is the "Godzilla" franchise, and that creature's American counterpart King Kong.
LOST WORLDS SCI-FI
Stories about the discoveries of lost civilizations, lost worlds or lost cultures
Lost Worlds is one of the oldest SF varieties. Sir Arthur Conan Doyle's novel The Lost World, based upon South America's then-mysterious 'tepui' plateaus, lent its very name to this subgenre. It has been adapted to film and television numerous times including BBC's 2001 television movie. Television's popular series Lost, from J.J. Abrams, continues the tradition with its bizarre isolated island.