Hey! I just had whisky last night. The lady was saying it's aged in wooden casks made of white oak.
Oh yum! that sounds awesome
A barrel or tun is cylinder and hollow with staves and metal hoops to hold it together.
Nice, what other cool info do you have?
Barrel
A barrel or cask is a hollow cylindrical container with a bulging center, longer than it is wide. They were originally made of wooden staves and bound by wood or metal hoops. 
Traditionally, the barrel was also a standard size of measure referring to a set capacity or weight of a given commodity. For example, in the UK a barrel of beer refers to a quantity of . Wine was shipped in barrels of . Barrel has also come into use as a generic term for a wooden cask of any
container more curved. Barrels have reinforced edges to enable safe displacement by rolling them at an angle (in addition to rolling on their sides as described).
Casks used for ale or beer have shives and keystones in their openings. Before serving the beer, a spile is hammered into the shive and a tap into the keystone.
The wooden parts that make up a barrel are called staves, the top and bottom are both called heads or headers, and the rings that hold the staves together are called hoops.