The classification of wines may be made or according to the grape or vine varieties used for the production, or according to the production area. The most famous and cultivated vines in the world are: among the red wines, Cabernet Franc and Sauvignon, Merlot and Pinot Noir; among white wines Sauvignon, Chardonnay, Riesling. The most important production areas are concentrated in Italy, France, Spain and California (Napa Valley). To date, however, the importance of an official classification has been replaced by the opinions and reviews from critics and wine journalists.
