When you’re not making it yourself at home, you might question what’s in your beer. As a result of this, German brewers came up with the Beer Purity Law, or the Reinheitsgebot, which was devised in 1516. This purity pledge, the first of its kind for beer, guaranteed the medieval beer drinker a certain level of quality when drinking a German brew. The pledge also indicated that all German beer must consist of only a few base ingredients: water, hops, malted barley and malted wheat, along with yeast.