In the Beer World, Chocolate and Spice Rule

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There are lots of great beer styles available right now, but you'd be forgiven for thinking it's all about imperial stouts. They count for 16 of the top 25 beers on beeradvocate.com and 17 of the top 25 at ratebeer.com.

The style originated in 18th-Century England, reputedly as a gift to the court of Catherine the Great—hence its original name, Russian Imperial. In recent decades American brewers have been crafting their own version, often called "double imperial." Confusingly, the newer, American style is often called simply "imperial stout." Take that, Anglo-Russian Entente.

Both styles pour like motor oil; they're high in alcohol, between 7 percent and 12 percent, with strong chocolate and malt notes. But Rocky Balboa would be proud: American doubles are even bigger than Russians—they're sweeter, more alcoholic, and much hoppier. And many American doubles bring a little something extra to the table: they're often aged, sometimes with vanilla beans, sometimes in whiskey barrels. Other times, they're brewed with coffee.

Imperial stouts are about as far from pale lagers as you can get. Which, in fact, may explain their popularity. They're the crowd-pleasing Cabernets of the beer world—heavy, boozy quaffs with popular flavors like chocolate, caramel, and spice. Think German chocolate cake in a bottle, doused in alcohol. High-alcohol beers of all kinds are hot right now, and the popularity of imperial stouts may come partly from the fact that, at 10 percent alcohol by volume or higher, all those flavors are needed for balance.

Imperial stouts resemble wine in another way. Any beer with ABV above 9 percent or so can be stored, and some—particularly imperial stouts—actually need a few years to mellow in the bottle. As a result, people collect, store, and sell them, just like they would fine wines. In some ways, they're even better than wine: for the price of a cellar-quality wine, a collector could buy a six-pack of an imperial stout, then drink one a year to see how it changes over time.

But there's something else going on with imperial stouts. They're not just highly regarded; they inspire cult-like behavior among their fans. That's in part because, like a Trans Am, imperial stouts are easy to customize. Brew them with cherries, age them in Scotch barrels, throw in some coffee beans from a prize-winning roaster, whatever you want. Release them in a limited edition, and suddenly people who might buy just a bottle or two will want one of each. Goose Island, in Chicago, has got this figured out: not only does it make Bourbon County Stout, aged in Heaven Hill whiskey barrels, but it makes hard-to-find varieties like Bourbon County Brand Coffee Stout, brewed with Intelligentsia espresso beans, and Bourbon County Stout Rare, aged for two years in barrels that formerly held 23-year-old Pappy Van Winkle, among the most expensive bourbons on the market.

Then there's the beer's extreme characteristics. Sure, you can do a keg stand, but are you man enough to down an entire bottle of Dogfish Head's World Wide Stout, at 18 percent ABV?

Then again, you'd be stupid to chug an imperial stout. Not only are they among the most expensive domestic beers, but they're also among the hardest to find. It takes a lot of skill, time, and resources to make a barrel-aged beer, something only the better craft brewers can handle. And despite imperial stouts' popularity, they're hardly session beers, and they're no fun on a hot summer day; as a result, most brewers limit their production to seasonal runs, producing limited amounts for a limited amount of time.

For reasons I've never fully fathomed, some of the best imperial stouts are released just one day a year. Like hajjis to Mecca, fans will travel to places like Portsmouth, New Hampshire, home of Portsmouth Brewing's Kate the Great, or Munster, Indiana, home of Three Floyds's Dark Lord, to get their hands on a few bottles.

At first glance, this makes no sense. Why would a brewery so severely limit the output of its best-known product? Most folks, even most beer lovers, will never taste a drop of Kate the Great. Then again, that's a great way to make sure everyone wants to try your beer.