Hops are important. As you've discovered, they're a critical part of making great beer.
Hops are a flowering plant that grows on a vine (or a "bine", technically), and they've been in documented use in brewing for close to 900 years. Specifically, brewers use the flowering portion of the female hop plant, scientific name of Humulus Lupulus. One could go on for hours about the science, history, and cultivation of hops, but we don't think you need such a myopic take on hops. We want to give you an understanding of their contribution to craft beer, their variety, and their flavor.
This is what a hop plant looks like
This is what a field of hop plants look like
These fields exist all over the world in moist, temperate climates. The most famous commercial hop-growing regions include the Pacific Northwest of the United States, the Hallertau region in Germany, the Czech Republic, and some dedicated areas of the U.K, Ireland, and eastern Europe. Note that we said "commercial" there, which essentially means they grow a LOT of hops (millions and millions of pounds of them). Hops are grown in much smaller amounts all over the world, including most of the continental U.S and Europe. Local hop farming is growing in the U.S at a fantastic rate, and there's much work to be done on that front. Educate yourself on locally grown hop centers and find the breweries in your area that use them.
Hops add bitterness, flavor, and aroma to beer. They are the balancing agent to sugary sweet backbone that the malt provides.
Specifically, hops have natural resins and essential oils that provide their uniquely identifiable flavor and aroma. Like any ingredient, different hop varietals contribute different flavors and aromas to beer, and a good brewer knows this. To get a little science-y for a minute, we'll identify these specific, critical chemicals in hops:
Alpha acids are (generally) responsible for bitterness. They are isomerized (basically dissolved) in the boil, which creates a lot of the perceived bitterness in a beer.
Beta Acids are also (generally) responsible for bitterness, but do not isomerize in the boil. These acids can oxidize quickly into rancid or "off" flavors, so high-beta acid hops are usually added at the end of the boil to avoid cooking them for too long.
When you're geeking out about hops, Alpha/Beta acids, along with essential oils, almost always come up in conversation. Now you know!
Hops can be used fresh, dried, or concentrated into pellets after their picked. Each of these forms have their advantages.
- Fresh Hops - These are whole-cone hops that have literally just been harvested (maximum a week ago). Beers and breweries like to use them (when they can get their hands on them) because they are highly aromatic, delicious, and full of those resins and oils we discussed earlier. However, most of the time this isn't possible. Beer is brewed year-round, and fresh hops are only available during a short window at harvest time. When you encounter a fresh hop ale or lager, get after it! It's bound to be good.
- Dried Hops - Not to be confused with the process of "dry-hopping", these are whole-cone hops that have been harvested and then quickly dried out to preserve their oils and resins. These hops have a shelf life, but it's been significantly extended past the fresh hop stage. Dried hops are very popular and used it many of your favorite craft beers.
- Pellet Hops - This is the most common, and most user-friendly, form of hop that brewers use in their beers. These are concentrated, crushed hop flowers that have been formed into pellets for storage and shipping purposes. They're usually packaged or vacuum-sealed and can last for a long time before a brewer needs to use them.
Hops have been cultivated by generations of farmers, botanists, and scientists worldwide into the modern hop varietals that we have available today. Remember, different hops contribute different flavors. Certain styles of beer can be directly identified by the hops that are used in that beer (think of that beautiful, lightly spicy note you get out of a classic Bohemian Pilsner, a hallmark flavor of Saaz Hops), such is the distinct flavor they impart in the brewing process. American hop farmers have cultivated numerous hop strains that have a strong, highly flavorful/aromatic presence in beer, and are home-grown right here in the great country.
An important part of discovering beer is being able to describe it. Adjectives are good. "Hoppy" flavors are usually described as:
What does this all mean? How do you know which beer has these characteristics? You need to taste the beer and have a conversation with someone! Great beer is fit to bursting with absolutely outrageous flavors, and people love to use them to describe the flavors found in certain beers. There are no hard and fast rules on how hops taste precisely to you, but you can get better at identifying these flavors and characteristics when you arm yourself with basic information about the beer and it's ingredients.