We age more than half our beers in wooden barrels, because they are the best vessel for our microorganisms. Yeasts and bacteria that are lingering in the wood (from previous beers) react with the microbes in our beer to form new flavours. This also happens when tiny amounts of oxygen seep through the wood and form chemical reactions of their own with the microbes. If there is Brettanomyces in the beer, it will eat the sugars naturally present in wood and excrete a wide range of aroma's in return. Any lingering taste of previous liquids in the barrel (e.g. wine, whisky, port, sherry) can rub off on the beer for even more depth. Finally, the type of wood used for the barrel can lend subtle notes like vanilla, while tannins give varying degrees of bitterness. Simply put: barrel aging gives our beer more character.