California is one of the most important winemaking regions in the world. There are several wine appellations in California. An appellation is a geographical indication used to identify where the grapes for the wine were grown. Each appellation, or AVA (American Viticultural Area) is based upon both a geographical designation (i.e. Napa County) and more precise ecological and environmental designation (i.e. Carneros region which is greatly influence by the cool fog off the San Pablo Bay)
Below is a list of the primary AVA in Calfironia with links to the winegrowers association for that region where you can obtain more information about that specific area.