Beer can be traced back 6,000 years ago to ancient Sumeria, in present day Iraq, though it's possible it existed well before that time. In ancient times, people drank beer through straws because the brew was unfiltered, and remnants were often bitter. In Medieval Europe, monasteries were centers of knowledge that refined brewing practices. Due to the lack of refrigeration, beer was mostly brewed at local breweries and served warm. In 1516, the Bavarian government passed purity laws that restricted the ingredients used to produce beer to hops, water, malted barley and malted wheat. Today, beer is a popular beverage in many countries and cultures.