The Reinheitsgebot, also known as the German Beer Purity Law, was enacted in 1516 in Bavaria. It originally allowed only three ingredients in beer: water, barley, and hops. This law aimed to ensure the quality and safety of beer, preventing the use of harmful additives. Over the years, the Reinheitsgebot has evolved, and today it is often seen as a symbol of German brewing tradition. While it primarily applies to beer, some modern interpretations allow for the inclusion of yeast as a fourth ingredient. The law has influenced brewing practices worldwide, promoting purity and quality in beer production.