Like many fringe movements before it, American craft beer was founded on a healthy flirtation with the extreme. In the battle against the light-lager swill that had held sway since Prohibition, trailblazing brewers deployed over-the-top hoppiness and super-charged alcohol content as weapons of mass destruction against the status quo.

As a result, the brief history of craft brewing has been rife with one-upmanship. There were the pioneers like Dogfish Head and The Bruery, who crammed as many oddball adjuncts as they could into each bottle to push the boundaries of a what a beer could taste like. There was the late-aughts Hoppiness Wars, fueled by high-octane beers designed to completely decimate your tongue—brews like Green Flash Palate Wrecker, Stone Ruination, and Mikkeller 1000 IBU, the IPA that touted its International Bitterness Units like a gift-store hot sauce pimping its Scovilles. And the early-2010s brought us the ABV Arms Race, with many breweries you’ve never heard of attempting to make the planet’s most alcoholic beer. The ultimate “winner” ended up being some minor Scottish outfit named Brewmeister, who in October of 2013 released a 67.5%-ABV offering named Snake Venom.

The problem, however, was that the industry had spent so much time crafting IBU-busting, ABV-shattering beers that the idea of moderation often fell by the wayside. You simply can't polish off a half-dozen vanilla bean-infused imperial stouts or barrel-aged barley wines in one sitting. The scene was set for a new beer style that would be "drinkable" without betraying the flavor-forward tenets of American craft beer.

Enter the session IPA.

All Day IPA was a breakout beer: It had the same manageable ABV of a Bud Light, while still delivering the hallmark hoppy aroma of an archetypal American microbrew. (Photo: Flickr)

It’s hard to track precisely the patient zero for the session IPA, but the term was knocking around in beer-nerd circles as early as the summer of 2009, and Founders All Day IPA appeared by mid-2010 (at the time it was called Endurance—All Day IPA). All Day's hybrid appeal was tough to ignore—it had the same manageable ABV of a Bud Light, while still delivering the hallmark hoppy aroma of an archetypal American microbrew. Sold in 15 packs of cans, the beer had the sort of cook-out cooler appeal that craft beer often lacked. Soon, All Day IPA was accounting more than 50% of Founders sales—the brewery even had to start running its canning line 24/7 to keep up with demand—and legions of imitators that quickly followed suit, led by instant hits like Lagunitas DayTime and Firestone Walker Easy Jack.

As a marketing ploy, the session IPA was a home run. But as the trend caught fire, its limitations as a beer style quickly revealed themselves. Some purist brewers refused to make them, arguing that a thin-bodied, low-ABV beer doesn't have the backbone to carry a boatload of hops. Likewise, drinkers who loved classic IPAs for their balance and complexity were too often disappointed by lack of nuance in the style. Like a cube of beef bouillon added to a bowl of vegetable soup, the hop onslaught couldn't make up for the style's inherent lack of oomph.

In its crisis of purpose, craft beer created a monster. The session IPA was not born out a desire to brew a better beer, but rather an attempt to meet a market demand. Yet by Frankensteining together the two major strains of domestic beer culture—the easy-going appeal of macro swill like Miller and PBR, and the just-add-hops ethos of craft—the style marks an important moment in the evolution of American brewing. Moreso than the pale ales and IPAs that preceded it, session IPAs offer an on-ramp for drinkers who are overwhelmed by craft beer’s more in-your-face offerings—just like Sriracha and Greek yogurt, they help nudge the mainstream palate towards more flavorful pastures. If a session beer like Sam Adams Rebel Rider can compete with porch-pounders like Miller High Life in the cooler, is that such a bad thing?

"In its crisis of purpose, craft beer created a monster. The session IPA was not born out a desire to brew a better beer, but rather from an attempt to meet a market demand."

Perhaps most excitingly, the session IPA may be a necessary bridge to milder styles that have long been marginalized in micro-brewing. Even as session IPA sales are up 199% since last year, craft breweries and their fans are starting to realize there are better options for their low-ABV needs. Look at the recent rise of the gose and Berliner weisse—more alcoholically restrained styles as well, but ones with more of a history and pedigree than the made-up session IPA.

Even better, look at this summer's rise of the craft pilsner. The hoppy machismo of craft beer seems to finally be waning, with quite a few notable craft breweries now making light lagers that, in theory, are no so different from the best-selling macro beers in the world. My local brewpub, Threes Brewing, is even calling these months the “Summer of Pils." Ignoring the more notable styles of IPA, saison, and wild ale which dominates his brewing for the rest of the year, Threes brewmaster Greg Doroski has released a series of pilsners of late less akin to American craft beer, and more similar to the Czech and German-style lagers that once informed the Buds, Millers, and Coors of the world. Doroski’s pilsners are flavorful, but most importantly, sessionable. You could easily spend an entire afternoon in the backyard of the brewpub, polishing off pils after pils.

Even those once-extreme breweries that helped build the craft-beer industry—breweries like Stone, Oskar Blues, and Surly—are now offering light lagers, showing that they're not the sole domain of corporate brewers. These craft lagers are not over-hopped like you'd think; they're not bold and brash, and they're certainly not extreme. They're simply solid lagers and pilsners—and they're selling well. It makes me wonder if perhaps the session IPA was the final stepping stone in getting craft-beer drinkers to quit worrying and finally embrace (or re-embrace) the lager, the most sessionable style of them all.

Heck, you can even drink Threes' pilsners from a branded brewery koozie—now, what says “session drinking” more than that?