Yeast + sugar = alcohol and CO2. With beer, the sugar comes from grains, primarily barley that's been soaked and cooked to make the glucose easily accessible. Toss in some yeast, trap the carbonation, and you have the sparkling treat that's fueled monks through long fasts and sports fans through paroxysms of joy and heartache.
Of course, if beer-making were that simple we'd all be drinking a single product sold in unadorned bottles labeled Beer, the same the world over. But like wine, beer is dependent on choices made by the brewer; on variations in water, grain and yeast; on additives like hops and other flavoring agents; and on cultural differences that have resulted in regional homebrews. Combined, those variables add up to hundreds of different brew recipes and thousands of different producers; each beer is unique.
But parse away the regional styles, subgenres and marketing language and you'll find that fundamentally there are only three different types of beer — ales, lagers and lambics. And it all comes down to how they're fermented.
Perhaps named for the beer-producing town of Lembeck in Belgium, lambics are produced with a large amount of unmalted wheat added to malted barley. This is old-school brewing, the pre-beer liquid left in giant, open, wooden casks in the brewery until whatever wild yeast happens to be drifting by lands on the liquid and gets to work. Once that happens, fermentation can take two to three years before that hitchhiking yeast has done its job. This style of wild fermentation isn't as happenstance as it seems — many breweries have been in operation for decades (or centuries) so the walls, floors, ceilings and vessels have essentially become impregnated with yeast. Some brewers even resist removing mold and growths in the brewery (or even in the casks) to encourage the strains they've come to like.
Lambics are generously hopped, since the resin and tannins in the flowers help preserve the beer through its long fermentation and lengthy aging. To temper the flavor of that mass of bittering agents, lambic producers use older hops that have more subtle aromas.
Many lambics are blended from several batches in order to produce a house style, and are sometimes mixed with additional sugar or flavored syrups, like the popular raspberry and peach varieties sold in the U.S. by Lindemans. Lambics tend, especially the unflavored varieties, to be exceptionally tart brews when young that temper to a refreshing, honeyed crispness with age.
Styles of lambic: Faro, Fruit, Gueuze (pictured)
Although wild fermentated lambics are how beer got started, ales have been around for well over a thousand years. Originally, ales used the same sort of haphazard, wild yeast that lambics do, but over time brewers realized that if they skimmed the foaming head that would develop at the top of the barrels, they could add it to the next batch to help jump-start fermentation. Mostly, they thanked God. Now, they thank science. Either way, over time this re-use of fermentation foam developed strains of yeast that were tailor-made for beer production.
The yeast used in ales is top-fermenting, which literally means that it gravitates toward the top of the beer to do its work. This type of yeast is resistant to heat, so ales can be fermented at fairly warm temperatures — usually from 60 to 75 degrees — which makes fermentation pretty quick. This also tends to develop the more complex, often fruity flavors that ales are known for.
Styles of ale: Brown, Dubbel, Pale (pictured), Porter, Stout, Trippel, Wheat
Lagers are relatively new to the beer scene, discovered by Munich-area brewers who realized that beer stored in caves in the Alps had a longer shelf life than other beers. This is because the yeast that can work at those cooler temperatures does its business at the bottom of the beer, so fewer strains of wild yeast can intermingle and cause problems for the beer. It wasn't until the 1800s, though, that brewers started to realize how and why the yeast worked the way it did. Thank Louis Pasteur for some of that.
In the early 1800s, Bavarian brewers started making the dark lagers that have made the region famous, although a bit of industrial espionage diluted their dominance. Legend has it that Jacob Christian Jacobsen — later a founder of Carlsberg Brewery — stole a sample of yeast from Spaten Brewery and smuggled it out under his stovepipe hat. Carlsberg eventually developed a pure strain of that yeast.
Because of the low temperatures needed — between 40 and 50 degrees — lagers ferment more slowly than ales, usually for around six weeks, but sometimes as long as a year. The flavors developed tend to be cleaner and less complex than ales, although the brewer can have a lot of say in that.
Styles of lager: Bock, Dunkel, Helles, Marzen, Pilsner (pictured), Schwarzbier