A wood- or barrel-aged sour beer is any lager, ale or hybrid beer, either a traditional style or a unique experimental beer that has been aged for a period of time in a wooden barrel or in contact with wood and has developed a bacterial induced natural acidity. Entries are aged with the intention of imparting the particularly unique character micro flora present in the wood. Sometimes wood aging is intended to impart the particularly unique character of the wood and/or what has previously been in the barrel, but wood-aged is not necessarily synonymous with imparting wood flavors. Wood character can be characterized as a complex blend of vanillin and unique wood character. Wood-derived character can also be characterized by flavors of the product that was in the barrel during prior use. These wood-derived flavors, if present in this style, can be very low in character and barely perceived or evident or assertive as wood-derived flavors. Any degree of wood-derived flavors should be in balance with other beer character. Usually bacterial and/or ―wild‖ yeast fermentation contributes complex esters and results in a dry to very dry beer. Ultimately a balance of flavor, aroma and mouthfeel are sought with the marriage of acidity, complex esters and new beer with wood and/or barrel flavors.