The current beer is usually produced from water, malt (mainly barley sometimes supplemented with other cereals) and hops (since the Middle Ages). The latter brings the scent and bitterness needed for each beer and acts as a natural preservative. This drink is consumed by pressure, bottle or can. The consumption of beer is the source of many festive events such as the Oktoberfest, the Mondial de la bière, the International Day of Beer; but also arouses many excesses such as drinking games such as beer-pong, Flip cup (en), beer bong (en), beer boot (de) or barathon. Very low alcohol versions (ranging from 2 ° to 0 °) are present on the market. Unlike other non-alcoholic drinks, they are made by the same processes as traditional beer. The production of beer is carried out industrially or artisanally in a brewery, while being possible by the individual.