Man, do people love hops. It seems every style under the sun is being "imperialized" with a heavy dose of the green stuff, and there seem to be more hop heads out there than uhh....human heads. And yet, not many people know what exactly goes into these beers—what makes each one different from the other. Hoppiness exists not merely as a linear scale of IBUs as it is often described, but as an array of flavors, aromas, and bitterness. Each hop variety (and there are dozens) is different, and identifying them is easier than you might think.
While it is usually fairly simple to identify the generally pungent, floral, citrusy, woody, herbaceous, peppery, earthy, resinous, or minty character associated with hops and "hoppiness," it is considerably harder to pick out a flavor and say, "Oh yeah! That's Northern Brewer!", especially when brewers are secretive about their recipes. With a set of proper expectations and a focused palate, though, you too, can be that obnoxious guy at the bar overanalyzing his beverage.
Let's start with the hops you're most likely to be sipping in your pint of American IPA: a group of hops known as the "Three C's." The Pacific Northwest's answer to continental Europe's Noble hops, the "Three C's" and their aromas epitomize IPA and pale ale—what some would call the cornerstones of modern American craft brewing.
Cascade is the hop that started a revolution. Developed by the USDA at Oregon State University for release in 1972, Cascade boasts a myrcene content of 45-60% of its total oil composition—this is the pungent aroma compound in thyme, marijuana, and yes—hops. Though you may not have known what it was called, you've definitely tasted it.
What to look for: Cascade is known for its trademark citrusy, floral, and most notably grapefruity aroma. Pick up a Sierra Nevada Pale Ale—though it isn't made with 100% Cascade hops as is often incorrectly repeated, it does use Cascade for all of its aroma and flavor hop additions. This is a pretty clean representation of the hop. For another take (why not make EXTRA sure while you're at it?), try Deschutes' Mirror Pond Pale Ale—this one is 100% Cascade.
Similar in flavor profile is the hop sometimes called "super Cascade:" Centennial. Boasting an elevated alpha acid content—this is the stuff that makes hops taste bitter—of 8 to 11%, compared to Cascade's 4 to 6%, Centennial yields a more potent bitterness when used in similar quantities.
What to look for: So it can be more bitter. How, you may wonder, are we supposed to tell the difference flavor-wise? It won't be easy. Aside from the elevated bitterness, Centennial is considered to generally be less citrusy and more floral than Cascade. Still—the primary flavor descriptors are the same—citrus, grapefruit, flowers.
If you can get it where you live, seek out Bell's Two Hearted Ale. (If you can get it where you live, and you're not already drinking it, then, shame on you.) This midwest classic IPA supposedly features 100% Centennial hops and is a beautiful beer to boot. Ignore the caramelly malt-driven characteristics and focus on the floral, grapefruity bitterness. That's Centennial. Dogfish Head's Hellhound on my Ale was also created with 100% Centennial, but the addition of lemon muddies the lines of distinction between citrusy hop flavor and actual citrus.
Columbus, thankfully, is more distinctive. Also known as Tomahawk, Zeus, or CTZ (Columbus, Tomahawk and Zeus, appropriately), Columbus is treasured for its high oil content, which yields an especially potent aroma. It smells something like earth, herbs, or marijuana, and often takes a supporting role providing depth and complexity to brighter hop bills containing citrusy top notes from Cascade, Centennial, or other hops. Though much of the beer community prefers to avoid using the word "dank" to describe beer, the resinous Columbus is often a driving force behind that description.
What to look for: Though there aren't a lot of 100% Columbus beers out there (you may have tried Mikkeller's Single Hop Columbus IPA when it was around), you'll taste it in many beers. Anderson Valley's Hop Ottin' IPA, Pyramid's Thunderhead, and Oskar Blues' Deviant Dale's IPA both feature the hop prominently, but if the next beer you pop smells like a Phish show, you're probably on the right track.
There's a lot of overlap between the above flavor descriptors and those for other very popular American hops, so reading this alone will not give you the ability to identify hops from across the room quite yet. Aside from trying the recommended beers I mention, the best way to start picking out hops in beer is to brew your own. Feeling and smelling hops as they go into your kettle can be an intoxicating experience in more ways than one, and you will always know exactly what's in the beer!