Vats are large, winery vessels used to store and ferment wine. They are typically made of wood or stainless steel and can hold up to several thousand gallons of wine. VATS are an essential part of the winemaking process, as they provide a controlled environment for the fermentation process to take place. The size of the vat is important, as it affects the amount of oxygen that can be introduced into the wine, which in turn affects the flavor and aroma of the finished product.