Fantasy is a much broader church than SF; if we're drawing Venn diagrams, you can probably characterise it as a really big circle overlapping at one side with the much smaller circle that is SF. (Items which explicitly blend magic with SF tropes occupy the overlap.) And the fantasy circle is pock-marked with smaller domains.

Here in the middle is your classic high fantasy, in the tradition of The Lord of the Rings—probably relying on a faux-mediaeval European setting, although there are variants off to one side or the other that use another cultural backdrop, usually imperial. (I can think off the top of my head of examples that leverage Roman, Classical Greek, Chinese, Japanese, or more unfamiliar settings: Mongol, Aztec, Dynastic Egyptian, and Vietnamese, to name but some.) A common problem with ancient empires is that they were pretty shitty places to live, unless you happened to be part of the happy 1% who were born into the ruling elite with the right configuration of genitals and the good luck to survive the typically horrendous infant mortality. (Let's face it: history is a crapsack world—even the maximally privileged lacked indoor plumbing, refrigeration, and modern conveniences such as not having more than half their children die before their parents. Yes, some people lived long, prosperous, happy lives: they're rare enough that historical biographies get written about them.)

Off to one side we have the burgeoning field inaccurately known as urban fantasy. You might think urban fantasy would mean fantasy set in built-up areas: but instead it's become synonymous with contemporary settings in the more-or-less modern world. (It overlaps at one edge with the sector of paranormal romance: PR is basically UF as an emergent sub-genre within the romance sector, and whether a story is one or the other is mostly a matter of how it's marketed rather than whether or not it has girl cooties; don't underestimate the romance field, it's a huge market that accounts for more than half of total fiction sales, and like any other genre category it contains the full gamut of qualities, from the sappy to the sublime.) We can stereotype UF as being about elves on motorbikes and PR as revolving around a girl with a gun and a tattoo living somewhere in small-town America and trying to deal with a smoking hot werewolf who wants to own her and an ancient and unaccountably stuck-in-the-past vampire love rat ... but that'd be selling it well short of its potential: the variations are enormous, possibly because unlike classical high fantasy settings, the modern world isn't a totally shitty dystopia that deprives everybody but the 1% of all agency so we can have narratives that don't require the protagonist to be a high Lord or Lady, at least at the outset.

Meanwhile, somewhere else on the petri dish we have the rapidly growing citadel of steampunk. Steam is optional and punk is definitely inappropriate, but ever since K. W. Jeter pinned the tail on the donkey in 1987 we've been stuck with the term of art (although the subgenre itself goes back considerably further). After much thought I'm inclined to say that steampunk when viewed as a fantasy sub-genre (as opposed to a fashion and design aesthetic) is a cognate of urban fantasy that is set in the near-historical past—using a setting 100-200 years past, rather than 500-1000 years ago. The key difference here is that it uses an accessible past: after all the last US Civil War pensioner (the young bride of a very old veteran) died in 2008. The Victorian/gaslight era is still remembered at friend-of-a-friend remove, whereas the Wars of the Roses have definitively moved into a purely historical context. (I live in an early Victorian apartment; my grandfather fought in the first world war: he grew up in a Victorian slum. And so on.)

So what are the peculiar shibboleths of these three sub-genres?

Let me start with urban fantasy, because it's closest to the present and hence slightly difficult to get the setting entirely wrong. I generally notice three common cock-ups when reading works of UF. The first can be summed up as "author is lazy, didn't do the research". In the era of StreetView and Google Maps, it's inexcusable to have your protagonist visit Edinburgh and describe the city in terms that position it north of the Firth of Forth, iron the terrain flat (the core is as steep as downtown Seattle), or get the architecture totally wrong. Ditto the basics of history that you can pick up by simply poking around Wikipedia for a few hours. I'll give works written pre-2001 a conditional pass on the research as the tools weren't so readily available, but newer authors have no such excuse unless they're deliberately confabulating.

My second UF shibboleth is historical contingency. There's one British UF series (I shall not name the guilty party) where we have wizards running amok on the streets of London. Indeed, there are whole orders of wizards, including battle mages, some of whom employ mooks with automatic weapons. Seven books into the series I'm pretty sure the author has racked up a death toll that drastically exceeds the British national murder rate—and much of it involves exchanges of gunfire, fireballs, and killer golems on the motorways. Yes, we have a society of wizards trying to keep the public from noticing, but really? It's symptomatic of a common failing whereby the hidden world exists in the shadows and the foregrounded world of the mundane is identical to our own, despite a medium-intensity civil war raging in the corners. Which leads inexorably to my third UF shibboleth, which is really a alternate variant of the second: the portrayal a world where the werewolves and vampires and superheroes are out in the open—but again, this world is culturally, politically, and ephemerally indistinguishable from our own. (Not all UF works fall into these traps, but they're surprisingly common. We have vampires with mind-control powers but politicians (and election count managers) don't take precautions against them. We have werewolves, but cops with guns don't routinely have a reload of silver bullets to hand. (Kudos to Kim Newman for actually taking this problem seriously in "Anno Dracula", and inventing a vampire-infested world that makes sense, for some value of sense. And before anybody in the back row shouts "Laundry Files!" at me, let me just say I've got it covered—but you'll have to wait for books 7 through 9 to see how it unfolds.))

I'm not going to spend a huge amount of time on Steampunk. SP is prone to exactly the same failure modes as UF—I think as a fictional form it's actually a subset thereof. A distinctive failure that SP is prone to is a wilful blindness to the constraints pre-20th century western society placed on women or people of color or the disabled. Yes, we have a lot of strong female protagonists of eccentric mien and independent means: yes, some people like that actually existed. But focussing exclusively on them runs the risk of whitewashing (or privilege-washing) a particularly dog-eat-dog nasty period of history (which, after all, is written by the victors) by gilding the hard edge of empire. Note: you don't have to go that way. Let me call out "Vermillion" by Molly Tanzer, and "Karen Memory" by Elizabeth Bear, as recent and excellent examples of SP that use female protagonists from non-privileged backgrounds to good effect.

A lesser problem that keeps cropping up in steampunk is what I call the gearbox-crunch—an attempt to portray a fake veneer of science and engineering to a fantasy setting, done so badly that the cogs jam and are unable to rotate freely. External combustion steam engines are lousy prime movers, energetically inefficient and requiring water as well as fuel: there's a reason we mostly don't use them any more, and it's in part the reason why powered heavier-than-air flight had to wait for the internal combustion engine. Robots powered by clockwork ... nope, don't get me started. It's very hard to frame a steampunk setting as scientifically plausible (as, for example, Stephen Baxter did in "Anti-Ice"), despite which many SP authors make the mistake of trying to do so, and fall flat on their faces. Significantly, the master of the sub-genre, Terry Pratchett (whose later Discworld stories are totally Steampunk) didn't go there. (And neither did Genevieve Cogman, who blogged here this month.)

Which leaves me looking at the shibboleths of high fantasy.

Hands up, everyone reading this who likes HF and who hasn't had some (even minimal or second-hand) exposure to Dungeons and Dragons?

D&D has a lot to answer for.

There was a telling passage near the end of the original AD&D "Dungeon Master's Guide" where Gary Gygax wrote about some of the source materials he and the folks at TSR drew upon when they were developing first-edition white box D&D and the later AD&D game. It ran the gamut from Tolkein through Fritz Leiber's Fafhrd and Grey Mouser stories, to Michael Moorcock's eternal champion yarns, Jack Vance's Dying Earth books, and a whole slew of other early-to-80s fantasy genre works. But it also introduced a bunch of its own baggage along the way, and much of it has leaked, overflowing like a blocked drain and contaminating the collective subconscious of genre fantasy authors who should bloody well know better.

I keep a bushel of cliches to hand. They act as warning signs that the author of an HF work was not paying enough attention to their world. For example: never trust a world where the currency consists of coins minted in precious metal in denominations divisible by 10 or 100: sooner or later it's going to blow out under the weight of its other internal contradictions. (If you want a magisterial perspective of what money was really like in the Olden Days, you could do worse than plough through the first 800 pages or so of "Quicksilver" by Neal Stephenson, or read up on the history of British currency.)

The currency fail I allude to is actually symptomatic of a deeper problem of perspective: which is that, while adopting a faux-historical setting, the authors haven't really bothered to try and understand history. You can approach the study of history from many different angles. The one that we commonly focus on in fiction is "the man on the white horse"—kings, heroes, queens, oh my. (The people books are written about.) But real historians also study climatology and demographics (the iron hands that dictate crop yields, the price of bread, and revolutions), and economics and high finance. Kudos to Seth Dickinson for his debut novel "The Traitor" (or "The Traitor Baru Cormorant", in the US), a secondary world fantasy which actually takes this stuff deadly seriously. (The eponymous protagonist is a meddling accountant, who starts wars or revolutions with the stroke of a pen by dictating fiscal policy.) It's rare to read a work of HF where the protagonists take money seriously—or worry about seigniorage, debasement, or where the money to pay for the next batallion of mercenaries is coming from when the crops are wilting in the fields. And this paucity of depth nags for my attention, because it can undermine the entire surface-level plot that ostensibly deals with heroes and kings, oh my.

Another warning sign: race politics as a shorthand for personality. Elves or Dwarves or Hobbits out of Tolkien hark hack to the prevailing world-view of the professor's own childhood, growing up in the hub of a world-empire prior to the first world war. He implicitly absorbed the values of imperial rule, under which nations were divided and consigned to privilege or servitude on the basis of a spurious perception of racial merit (or rather, utility to the imperial masters). Here in the real world, human beings are graded on a curve. Moreover, human beings breed back towards the average. (Einstein's offspring were not notably world-changing genii.) The pernicious myth of race is exactly that: and the race-essentialism of Tolkeinian high fantasy leads down some very unsavoury alleys. It gets even worse when we consider the pernicious implications of the D&D alignment system—the half-baked dualism of good versus evil, crossed with an orthogonal dimension of law versus chaos, to which entire races are consigned. Religious eschatology, principally Christian, creeps in via this schema because the doctrine of original sin is pretty much baked into this—and contrary to what many Brits and Americans might believe, this isn't actually a univeral belief framework shared among all faiths: it seems to have crept into early Christianity via syncretistic assimilation of chunks of Zoroastrianism (along with other items that went into the melting pot: the Cult of Mithras, the Cult of Isis, early millenarian Jewish mysticism, and a whole bunch of Roman-era pantheons who were repurposed as hierarchies of saints). It's a framework that implicitly condones genocide and atrocity, because it inherently denies the possibility of individual reform. It's occasionally deconstructed to brilliant effect, as in Mary Gentle's "Grunts", but for the most part it's reprehensible: the sort of genre trope one might have expected of the pulp literature that flourished under the aegis of a victorious Third Reich.

A final hideous shibboleth of high fantasy is the folks-were-stupid-in-the-olden-days trope. We frequently see peasants portrayed as thick-witted or slow, societies as static, merchants as not having the wits to bargain their way out of a paper bag, and everyone except the hero-protagonist as lacking in innovative drive. But this just ain't true. Leaving aside the issue of the disease and parasite burden under which the people of much HF worlds labored (hey, anyone else watched "Monty Python and the Holy Grail" lately? Or "Jabberwocky"?), historical societies weren't static. They existed under equilibrium constraints imposed by their local climate, the Malthusian carrying capacity of the land, available crops and parasites, and with random noise and fuzz imposed from the top down by whoever was trying to make themselves King or big themselves up that month. Most mediaeval noble families didn't last more than a handful of generations, any more than modern millionaire dynasties last forever; peasants weren't stupid so much as they were cautious, for a rash experiment in agricultural innovation could doom your family or village to slow starvation over the next year. And the lack of decent energy sources and high purity materials (not to mention the propagation of erroneous beliefs in natural philosophy) manacled a ball and chain around any would-be reformer's ankle before they crossed the starting line. Oh, and while I remember? Horses are not magical hay-burning all-terrain motorbikes, m'kay?

(Actually, there are so many goddamn shibboleths capering and hooting and generally making whoopee throughout the high fantasy field that Diana Wynne Jones wrote a book about them—The Tough Guide to Fantasy Land. It's sort of like TVTropes for high fantasy: if you enjoy reading the stuff or playing AD&D you should probably avoid it, but if you want to write HF you need to memorize it.)

Anyway, enough of my pet fantasy peeves. You'll note I completely ignored a whole bunch of fantasy subgenres (from secondary world fantasy through the gothic novel of the uncanny). What gets you worked up when you read fantasy?