<P> Beer was spread through Europe by Germanic and Celtic tribes as far back as 3000 BC, and it was mainly brewed on a domestic scale . The product that the early Europeans drank might not be recognised as beer by most people today . Alongside the basic starch source, the early European beers might contain fruits, honey, numerous types of plants, spices and other substances such as narcotic herbs . What they did not contain was hops, as that was a later addition, first mentioned in Europe around 822 by a Carolingian Abbot and again in 1067 by abbess Hildegard of Bingen . </P> <P> In 1516, William IV, Duke of Bavaria, adopted the Reinheitsgebot (purity law), perhaps the oldest food - quality regulation still in use in the 21st century, according to which the only allowed ingredients of beer are water, hops and barley - malt . Beer produced before the Industrial Revolution continued to be made and sold on a domestic scale, although by the 7th century AD, beer was also being produced and sold by European monasteries . During the Industrial Revolution, the production of beer moved from artisanal manufacture to industrial manufacture, and domestic manufacture ceased to be significant by the end of the 19th century . The development of hydrometers and thermometers changed brewing by allowing the brewer more control of the process and greater knowledge of the results . </P> <P> As of 2007, the brewing industry is a global business, consisting of several dominant multinational companies and many thousands of smaller producers ranging from brewpubs to regional breweries . As of 2006, more than 133 billion litres (35 billion gallons), the equivalent of a cube 510 metres on a side, of beer are sold per year, producing total global revenues of $294.5 billion (£ 147.7 billion). In 2010, China's beer consumption hit 450 million hectolitres (45 billion litres), or nearly twice that of the United States, but only 5 per cent sold were premium draught beers, compared with 50 per cent in France and Germany . </P> <P> The process of making beer is known as brewing . A dedicated building for the making of beer is called a brewery, though beer can be made in the home and has been for much of its history . A company that makes beer is called either a brewery or a brewing company . Beer made on a domestic scale for non-commercial reasons is classified as homebrewing regardless of where it is made, though most homebrewed beer is made in the home . Brewing beer is subject to legislation and taxation in developed countries, which from the late 19th century largely restricted brewing to a commercial operation only . However, the UK government relaxed legislation in 1963, followed by Australia in 1972 and the US in 1978, allowing homebrewing to become a popular hobby . </P>

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