Cava is a Denominacion de Origen of slightly unusual formation. Based in-and-around the Penedés hills, south of Barcelona in Catalunya, the appellation applies in minor volumes to other regions, such as Rioja and Navarra. Cava production is 'methode champenoise', called 'method traditional' in Spain. Typically, only white grapes are used. Chardonnay is making inroads, but the traditional white varieties of the region predominate: Macabeo (macca-bow), picked earliest, growing best near the coast; Xarel.lo (char-rell-low) from the Penedes depression, and Parellada (pa-rey-yada) from the precoastal mountain range. Malo is rarely affected, due to the relative warmth of Penedes.
D.O. Cava is a curious wine region, as it is, technically, non-geographic. Mostly, Cava is produced in the wine region of Penedes, an hour south of Barcelona, and just inland from the coast. Although nearly all sparkling Cava is produced here, there are small productions licensed in other areas, and thus Cava is a D.O. which limits itself to concerns about how, not where, Cava is grown and made. That said, you may well go your whole life without tasting a non-Penedes Cava.