A keg is a small barrel.
Traditionally, a wooden keg is made by a cooper and used to transport items such as nails, gunpowder, and a variety of liquids.
In recent times, a keg is often constructed of stainless steel. It is commonly used to store, transport, and serve beer. Other alcoholic or non-alcoholic drinks, carbonated or non-carbonated, may be housed in a keg as well. Carbonated drinks are generally kept under pressure in order to maintain carbon dioxide in solution, preventing the beverage from becoming flat.