A barrel is a hollow cylindrical container with a bulging center, longer than it is wide. They are traditionally made of wooden staves and bound by wood or metal hoops.
Wine barrels typically come in two hoop configurations. An American barrel features 6 hoops, from top to center: head- or chime hoop, quarter hoop and bilge hoop (times two), while a French barrel features 8, including a so-called French hoop, located between the quarter- and bilge hoops (see "wine barrel parts" illustration). The opening at the center of a barrel is called bung hole and the stopper used to seal it is a bung. The latter is generally made of white silicone.