Last week, I conducted a curious experiment. A friend at a brewery had sent me a Ziploc bag of American hops, the flower buds from the hop plant that are used to flavor beer. I just went wild when I opened the bag—the scent was so intensely grassy, citrusy, and floral. It was like inhaling what a well-balanced India Pale Ale (IPA) should smell like. I took a glassful of these dried hops around the office to gauge reaction, and it was easy to spot the true sensualists in the crowd, of which there were many. While that's probably not a big surprise, what was fascinating was that several self-proclaimed non-beer drinkers went crazy for the intense hoppy bouquet. After all, these intoxicating aromas are essentially what you should smell and taste if you sip a well-crafted American IPA, rapidly becoming one of the most popular styles of beer in the country.

The first IPAs were brewed in London in the 1700s and designed for export to English soldiers and merchants in India. Thanks to the heady dose of hops, which served to preserve freshness and mask any staleness, these pale ales were excessively bitter, high in alcohol, and brewed to withstand anything a five-month sea voyage could throw at them. Modern American IPAs are still characterized by the liberal use of hops (when it comes to flavor, more is more) and tend to be high in alcohol (more than 5.5 percent), but other than that they show little resemblance to their imperial forebears. For one thing, these modern incarnations are meant to be enjoyed fresh instead of aged. And in true democratic form, American IPA styles vary greatly from West Coast to East.

The American versions, particularly those brewed on the West Coast, have been labeled "extreme beers," owing to their amped-up use of hops. And in turn, their devotees are appropriately called "hop heads." Take Lagunitas Brewing Company in Northern California, which helped pioneer the West Coast style in the mid '90s. "In hops and alcohol, we're bigger than the British," says Tony Magee, founder of Lagunitas. "We had to find ways to differentiate ourselves from traditional European styles. We love the flavor of American hops—they're so distinct with that resiny flavorful bitterness—so we took our pale ale and upped the malt by 35 percent and the hops by 40 percent. We figured if some hops is good, then more is better." The Lagunitas IPA has a pleasant amount of bitterness, with an IBU (International Bitterness Units) of 45.6. To give you some means of comparison, British versions hover around 30 IBU. Meanwhile in Minnesota, Omar Ansari at Surly Brewing Co. has turned up the dial on hops to a full roar for what he calls "a tempest on the tongue" with his Furious IPA, which has a whopping 99 IBU. At the Maui Brewing Co., the Big Swell IPA features a comparably modest 60 IBU, and is as refreshing as one might expect from a brewery in a tropical locale. But whatever their flavor differences, one important commonality that all American craft IPAs have is that they go remarkably well with food, particularly spicy and fatty dishes.

Although the history of IPA doesn't tie directly into Indian cuisine, IPAs are a surprisingly good match with the cooking of the subcontinent, as they are with Thai, Mexican, Chinese, and Cajun food, as well as classic American barbecue. "The cutting power of the bitterness with spice or with oils and fats makes IPA a much better match with spicy cuisine or barbecue than wine," says Garrett Oliver, author of The Brewmaster's Table and editor of the forthcoming Oxford Companion to Beer. Oliver is also brewmaster at Brooklyn Brewery, which turns out a traditional interpretation of British IPA. "If you think of heat on a scale of one to ten, Alsatian GewÃ¼rztraminer can take you to three, German Riesling to about four, and after that you're distinctly in IPA territory."