This is the process of maturing wine or spirits in barrels or casks prior to bottling. This process allows young beverages to soften and absorb some of the wood's flavors and tannins and allows the flavors to become concentrated through slight evaporation through the wood. While oak is the overwhelming wood of choice for wood aging, mesquite, hickory, pecan, apple, orange, and cherry wood can also contribute unique qualities to wines or spirits aged with their chips or shavings. The taste a wood tends to impart in wine is that of its smell.
See also: Maturation.