Wine barrels are large containers traditionally made from wood, primarily oak, used for aging and storing wine. The wood allows for a slow exchange of oxygen, which helps develop the wine's flavors and aromas over time. Barrels can vary in size, with the standard size being around 225 liters, known as a Bordeaux barrel. The process of making wine barrels involves carefully selecting and toasting the wood, which enhances the wine's characteristics. Different types of wood and toasting levels can impart unique flavors, such as vanilla or spice, to the wine. Properly maintained barrels can be reused for several years, making them an essential part of the winemaking process.