The German Beer Purity Law, known as the Reinheitsgebot, was established in 1516 to regulate the ingredients used in brewing beer. It originally allowed only three ingredients: 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 in 1987, it was expanded to include yeast as a permitted ingredient. Today, it remains a significant part of German brewing culture, promoting traditional methods and high-quality standards in beer production.