IBU stands for International Bitterness Units, which is a scale used to measure the level of bitterness in beer. Specifically, IBUs measure the parts per million of isohumulone from hops in a beer, which gives beer bitterness. The IBU scale can range from 0 to 120+, but at this point, the human tongue can’t taste any more bitterness. The IBU scale was invented because it felt important to measure how bitter a beer was, and the assignment of numbers helps with conceptual understanding. However, IBU isn’t the only indicator of how a beer may taste, as malt/grain character and sweetness can balance out bitterness in a beer. It’s not uncommon to see a beer with a high number of IBUs that doesn’t actually taste bitter. For example, a technically bitter, high-IBU amber ale can taste sweet as a result of the deep amber malts used. Similarly, a German pilsner can have a low IBU number and taste quite bitter because of its lean, crisp malt character. The IBU scale can be useful for identifying the bitterness level of a beer, but it is not the only factor that determines the taste of a beer.