Wood aging is an important part of wine production. The process involves wine being stored for a period of time in a wooden barrel. This gives the wine more complexity and firmness. Oak wood is the most commonly used wood for wood aging, because it is strong and allows the right amount of oxygen to pass through. However, winemakers have to make choices about what kind of wood, size of the barrel, old or new wood and the toasting of the barrel. Wood aging is an expensive process, so winemakers should consider carefully whether to use it.