Barrel fermentation is the process of fermenting wine—typically white—in oak barrels rather than stainless steel tanks, allowing the wine to integrate oak influence from the earliest stage. This technique enhances texture and complexity, often contributing flavors like vanilla, toast, spice, and a creamier mouthfeel due to lees contact and micro-oxygenation. Commonly used for varieties like Chardonnay, it can create a richer, more layered style of wine.