Hops are the flowers, or cones, of a plant called Humulus lupulus. They are one of the four main ingredients in beer, along with malt, water, and yeast. Hops help to keep beer fresher for longer, help beer retain its head of foam, and add aroma, flavor, and bitterness to beer. Hops are divided into two general varieties: bittering and aroma. Bittering hops have higher alpha acids, making them more economical for bittering beer, while aroma hops tend to have more essential oils that contribute much of what people understand as “hoppiness”. Hops are added by brewers during the boil, which is one of the earliest steps in brewing. The alpha acids inherent in hops release their bittering elements, which are necessary for adding bitterness to beer and keeping it from tasting too cloying. Hops are also used to add aroma and flavor, most notably in beers like pale ales and IPAs. Every single beer on the market today contains hops. If they didn’t, they would be a “gruit” which is basically a beer that, instead of hops, uses herbs like bog myrtle, yarrow, heather, or juniper.