If Speculative Fiction is part of the larger category of imaginative writing, then within that is the category which I’m most interested in, which is sff / scifi / science fiction and fantasy. The anagram sff (usually lower case) is often used as an abbreviation for Science fiction and fantasy.
An alternative term is sci-fi, but this has acquired a derogatory term that I do not share (I tend to use the spelling scifi, without the hyphen)
In the above diagram, five categories are listed, representing a basic sliding scale of realism from less to more real
Fantasy is mythic or imaginative storytelling that uses a medieval (or sometimes now modern urban) setting and non-technological tropes. An analysis of Fantasy deserves a whole page in itself, although it’s not really my thing except when it overlaps with space opera as “science fantasy” or “space fantasy”. Worldbuilding is very important in High Fantasy and mythic fantasy, and it’s rare to find a book in this genre that doesn’t come complete with maps, a la Tolkien. Dark Fantasy has little or no worldbuilding, and overlaps with or is sometimes included under Horror. In general, High Fantasy includes Dark Fantasy creatures but not vice-versa. Not included in the above diagram is Urban (contemporary) Fantasy. which also includes Supernatural Romance.
Sci-Fi refers to Hollywood style science fiction, which tends to be low on the realism scale and is defined by certain tropes like laser guns that make a pew! pew! noise and shoot bolts that only travel at the speed of tracer rounds, spaceships where down is perpendicular to the direction of travel, aliens that resemble human actors but with rubber prosthetics stuck on their heads, and English as the universal language, even spoken by aliens who have never contacted humans before. This is also known as “Space Opera“. Examples include Star Trek, Star Wars, Babylon Five, Farscape, Firefly, Guardians of the Galaxy, and the upcoming Valerion.
Quoting Wikipedia “The term “sci-fi” was suggested as an abbreviated term for “science fiction” by magazine editor, science fiction writer and literary agent, a founder of science fiction fandom, Forrest J Ackerman in 1954, by analogy with the then-cutting edge term “hi-fi”. Ackerman was the literary agent for science fiction authors Ray Bradbury, Isaac Asimov, A.E. Van Vogt, Curt Siodmak and L. Ron Hubbard. He pronounced his new term as “sigh figh”. ”
Skiffy – many science fiction purists despised sci fi, which was frequently associated with bad or unscientific TV and movie writing, As early as the 1970s some members of science fiction fandom began to pronounce sci-fi as “skiffy”, rejecting alien monster movies from true science fiction, which they refer to as “SF.” The problem is that to the general public “SF” means “San Francisco.”
The American Sci-Fi Channel only made things worse by hosting shows like Buffy the Vampire Slayer as well as more conventional TV science fiction like Star Trek. Later “skiffy” was also adopted by fans and writers who reject the Sci-Fi” vs. “Science Fiction” argument. Some SF authors like Mike Resnick identify as Skiffy Writers. In 2009, the Sci-Fi channel was renamed Syfy for branding purposes, but also I remember reading somewhere to distance itself from conventional science fiction
Soft SF – this category is adapted and abbreviated from Wikipedia – List of Genres Soft science fiction typically deals more with cultural, social, and political interactions than with hard science problem solving.
- Feminist science fiction: tends to deal with women’s roles in society. It poses questions about social issues such as how society constructs gender roles. Some of the most notable feminist science fiction works have illustrated these themes using utopias to explore a society in which gender differences or gender power imbalances do not exist, or dystopias to explore worlds in which gender inequalities are intensified, thus asserting a need for feminist work to continue.
- Military science fiction: told from the point of view of the military, or a main character who is a soldier in the military. This is essentially is the addition of science fiction elements into a military fiction story (some military science fiction stories fit at least somewhat in the “hard science fiction” subgenre as well.)
- Punk: Several different Science Fiction subgenres, normally categorized by distinct technologies and sciences. The themes tend to be cynical or dystopian, and a person, or group of people, fighting the corruption of the government. Include Cyberpunk, Postcyberpunk, Retropunk, Steampunk, Biopunk, Nanopunk, etc Nanopunk can be considered hard’ or ‘soft’, depending on one’s views regarding the plausibility of nanotechnology
- Social science fiction: concerned less with the scientific background and more with sociological speculation about human society. Exploration of fictional societies allows science fiction to criticize the contemporary world and to present solutions, to portray alternative societies
- Space opera: A story characterized by the extent of space travel and distinguished by the amount of time that protagonists spend in an active, space-faring lifestyle. Some space operas have quite detailed worldbuilding.
Hard SF or Hard science fiction involves detailed, well-researched, and plausible science, but trends towrads dryness and rather arid problem solving. See the Sliding Scale of Realism page. Obviously, some of these categories are somewhat arbitrary