There’s a torpedo joke in here, but it’s up to you to make it.

It’s (usually) easy to tell if a story is Genre, which is within-our-genre-speak for Science Fiction, Fantasy, and Sometimes Horror. Does it have dragons? Does it have ray guns? Which animals talk, and why?

Then you have to explain that yes, you write fantasy, but– no, not like Tolkien, no, not like Harry Potter, seriously, it’s, um….

This is where subgenres come in. The lines between subgenres are more obviously loose than the line between Genre/Spec Fic/SFFandsometimesH, mostly because there are more of them and comparatively fewer books that don’t sit near one. These are my own definitions and recommendations, and I have probably forgotten some hugely important subgenre– or I simply don’t know about it. If you have a book, movie, TV show, whatever, to recommend, comment. Contrary to popular belief, I don’t read everything.

Space Opera: science fiction with lots of spaceships and an epic plot. This tends not to have a lot of rigorous science, but quite a lot of action. Star Wars is space opera.

Hard SF: science fiction that relies on a lot of very accurate science. This often seems to center on the science and its effects. People who like it say it’s rigorous and intellectually stimulating, people who dislike it say it lacks character and plot.

Near-Future SF: exactly what it sounds like. Instead of being set a hundred years in the future, when everything has changed, it’s set in 2020, when enough can be expected to change that the writer can put in some interesting tech, but not far enough away that the tech can be basically magic.

Science Fantasy: what people call Star Wars when they don’t want it to be Science Fiction. I don’t agree with many applications of this because the failure mode of Science Fiction is not Fantasy. A really great Fantasy story doesn’t become SF, does it? But this is, loosely, what you get when you have an SF setting and fantasy trappings. This one borders Space Opera and may have the same relationship to it as Paranormal Romance does to Urban Fantasy.

Military SF: science fiction with lots and lots of military in. These are war books, no question. They are probably published by Baen, which means you can spot the cover a mile away. Elizabeth Moon’s science fiction is mostly military SF; look up the Vatta’s War books, starting with Trading in Danger, to get an idea. David Drake has also been recommended.

Cyberpunk: in which computers take over the world. William Gibson’s Neuromancer is cyberpunk. Everyone is wired, a lot of the plot revolves around the internet. If you read a lot of cyberpunk, what do you recommend?

Steampunk: probably has an airship on the cover. This is pretty common right now, partly because the costumes are interesting. If you have Victorian-era technology doing things beyond what it actually did, the story is probably steampunk. Steampunk can be fantasy or science fiction. Examples include Cherie Priest’s Boneshaker and Scott Westerfeld’s Leviathan.

Alternate History: the other subgenre likely to have an airship on the cover. This is when you ask, “What if the Confederacy had won the American Civil War?” or, “What if Hitler had won World War II?” and run with it. I don’t read straight alternate history– mine always have magic in. If you do read alternate history, who do you recommend? I’ve heard Harry Turtledove is good. Jo Walton’s Farthing also got a lot of attention.

Urban Fantasy: blurs into Paranormal Romance, which is a great example of one genre scorning another. How would we ever survive if we didn’t have someone more mockable? Urban Fantasy began as ‘any fantasy story set in a modern-day city’ and so you will find some people pointing to Emma Bull’s War for the Oaks and Charles de Lint as prime examples, then sniffing at everything published recently as trashy romance. Urban Fantasy has since gone through the Anita Blake books to mean darker fiction set in a modern-day city, often with vampires, werewolves, and/or demons. There is often a strong romantic component, a reasonable series structure, and a tattooed woman wearing the Urban Fantasy Belt on the cover. The modern-city setting doesn’t seem to be the defining mark of the genre at this point.
If you get me started, I will go on for days about paranormal romance, urban fantasy, genre scorn, and feminism. No, really. Consider this your warning.
For old-style urban fantasy, look at the aforementioned Emma Bull, Charles de Lint, and Peg Kerr’s The Wild Swans. For new-style, I recommend Patricia Briggs’ Mercy Thompson books, starting with Moon Called, Ilona Andrews’ Kate Daniels books, starting with Magic Bites, Holly Black’s Valiant, and Jim Butcher’s Dresden Files, starting with Storm Front.

High Fantasy: Tolkien. Secondary world, technology from the medieval or Renaissance period, peasants and kings and a Quest. It’s been a while since I read anything I’d call High Fantasy, but then, I am not always interested in labeling my subgenres. Guy Gavriel Kay’s Fionavar Tapestry is High Fantasy.

Epic Fantasy: like High Fantasy, only longer and less folkloric. Robert Jordan’s Wheel of Time. Kate Elliott’s Crown of Stars, starting with The King’s Dragon. Patrick Rothfuss’ The Name of the Wind. Large, sweeping stories that often involve the fate of the world, or at least large, heavy books. To me, High Fantasy is Epic Fantasy only more poetic. The two subgenres might overlap more than I think. Argue in the comments, please.

Dark Fantasy: fantasy with some horror in. Neil Gaiman’s work comes to mind. I think Anne Bishop’s Black Jewels books are Dark Fantasy, too, but there might be two subgenre-identities, as with Urban Fantasy. Do you read it? Help me out here.

Fantasy of Manners: this is the genre least likely to contain anything genreful. Like steampunk, Fantasy of Manners is often set in the past. Unlike steampunk, Fantasy of Manners concerns itself less with factories and workshops than drawing rooms and duels. Ellen Kushner’s Swordspoint and The Privilege of the Sword are two of the prime examples of Fantasy of Manners, and they take place in a secondary world without much magic. Patricia Wrede and Caroline Stevermer wrote Sorcery and Cecelia and its sequels, epistolary novels set in the Regency era.
Fantasy of Manners is sometimes called Mannerpunk, but frankly, I think this appellation vulgar and prefer to avoid it.

Magical Realism: the twee description of this is ‘slipstream/interstitial in Spanish’ or ‘fantasy your literature professor tells you to read’.

Young Adult: Anything else can be part of Young Adult. This means it’s written for an audience whose age centers around high school, including junior high and college students. The audience younger than Young Adult is Middle Grade, then Children.

Postapocalyptic: exactly what it sounds like. This is usually SF, but I have read some good postapocalyptic fantasy. The world as we know it has ended. The story may be an adventure, an exploration of human nature, a bleak dystopia, anything.
SF postapocalypses: are not something I read very often. Suggest away!
Fantasy postapocalypses include Patricia Briggs’ The Hob’s Bargain and Kate Elliott’s Crown of Stars books, though the latter are also preapocalyptic. I would accept an argument that Ilona Andrews’ Kate Daniels books are postapocalyptic.

Singularity: this is kind of like Zombies: it is a batch of things people poke at. It’s cyberpunk and postapocalyptic, ish. Um. Help?

Zombies: feature the walking dead. I tend to say ‘zombie narrative’ for a specific type of book, like Carrie Ryan’s The Forest of Hands and Teeth or, honestly, any run-from-dead story. For a better look at the idea of zombies, look for the two The Living Dead anthologies edited by John Joseph Adams.

Slipstream/Interstitial: is by Kelly Link. This is sort of what lies on the lines between subgenres and genres and sort of its own thing. Go to a con, find the panel that tries to define it, understand that the panel never will.