A wine cask is a large neutral wooden container that looks a whole lot like an oversize barrel. Though casks are used to age and store wine, they differ from smaller oak barrels in that they are not expected to impart a lot of oak flavor to the wine. Subsequently, they usually are not replaced after a few years of use. In fact, the venerable casks at some wineries have elaborate carvings, such as those at Sonoma Valley's Sebastiani Vineyards, which has the world's largest collection of hand-carved casks.