The basic ingredients of beer are water, starch, brewer’s yeast and hops, and it is produced by the saccharification of the starch and fermentation of the resulting sugar. Starch and saccharification enzymes are most commonly derived from malted cereal grains such as malted barley and malted wheat. Unmalted maize and rice are used to lighten the flavour, while hops add a bitter flavour and act as a preservative. The process of making beer is called brewing and a place that produces commercial beer is called a brewery, while producing beer for non-commercial use is called homebrewing. Beer is considered to be the world’s oldest fermented beverage and is currently the third most widely consumed beverage in the world, after tea and water. The most common strength of beer is between 4 and 6% ABV and varieties include lager, pale ale, stout and wheat beers.