Hops are the flowers of Humulus lupulus. Known primarily to beer drinkers and brewers, it’s through the distilling community’s close ties to the brewing community that we first saw hops becoming a common ingredient in gin. Today, many of the distilleries playing with hops are also breweries.
In gin, hops can be added after distillation for a style of flavored gins known as “hopped gins,” which feature an aggressive bitter, citrusy flavor like you might get in an IPA. Hops can also be distilled, which results in a less bitter and more floral/citrus note from the hops.