Beer is one of the most popular drinks around the world. Brewed as far back as 4000 BC by the Sumerians, beer is also one of the oldest alcoholic drinks still in production. One of the reasons beer is so popular is that is easy to make and require few ingredients. In fact, there are only four ingredients in beer: water, barley, yeast, and hops. All beers are made with the same ingredients; the only variation between them is in the amount used of each ingredient, plus variations in brewing. For example, ale must be fermented for 21 days, while lagers require 35.

While the ingredients used are simple, the standards are high. For example, the water used to make beer must be purified, and the barley malt used is screened for imperfections in the growth and quality. The first step in making beer consists in filtering the barley through a pipe, which adds water to the grains in order to help them release more sugars. The grains are then mashed in a giant metal pot that breaks down the starches and ferments the mix.

After this, the mix is recirculated through a filter and more water is added. This step, called "sparging," is essential to make sure all sugars are being extracted from the grains. The mix, which is not yet beer, is then boiled for 90 minutes in a special giant kettle with a double bottom, which allows steam to circulate. Hops are added at this point to provide the bitter taste characteristic of beer, and then the mix is drained to separate the liquid from the solids. Once the liquid has cooled, yeast is added and the preparation is stored to allow it to ferment. Flavors are added at the end.

Making beer is a delicate process, as the liquid changes containers many times, and breweries need to guarantee that the mix does not get contaminated at any point. Beer can be brewed at home with a very simple set of materials available at home brewing stores. The basic difference is that home-brewed beer does not taste the same batch after batch, because it is almost impossible to get the ingredients to match the exact same measurements every time.