Storage of the wine in a barrel with the purpose of subjecting it to a maturing process. Barrels can be made of various materials such as stainless steel, wood, concrete or ceramics, but when it comes to barrel ageing, a wooden barrel is usually meant. Barrel size, barrel age, type of barrel wood and the method of production have a great influence on the course and length of the maturing process. The type of barrel finally used is mainly determined by the desired style of wine. Very often, however, it is not clear from wine descriptions in connection with vinification in which type of wooden barrel the wine has been matured. This is because the type of ageing is not required by wine law.