Beer is made from malted barley, water, hops, yeast and sometimes other grains or sugars. The basic brewing process involves malting the grain to release enzymes, mashing to convert starches to sugars, boiling the wort with hops, fermenting with yeast, maturation and packaging. There are two main types of beer - ales which use top-fermenting yeast and are ready more quickly, and lagers which use bottom-fermenting yeast and take longer to produce. Beer should be served between 2-5 degrees Celsius in clean, appropriate glasses to best enjoy its flavors and aromas.