Wine Classification - by Region or by Wine Type?

There are two standard methods of classifying wines - by region ("Bordeaux"), and by grape type ("Cabernet Sauvignon"). In established areas (basically in Europe), wines are strictly defined by where they're grown. Champagne only comes from the Champagne region of France. Port is only the wine grown in a certain valley in Portugal. If other areas make similar wines, even using the same grapes, they use a different name. Most European wines do NOT list the grape varietal on the bottle label. They only list the region the wine comes from, and expect you to know what that means.

In newer areas (the US, South America, Australia, etc.), wines are usually promoted based on the grapes which they are composed of. For example, even though California has a region called "Napa Valley", that region actually puts out a huge variety of wines. So when you buy a Napa Valley wine, it will say on it that it is a "Chardonnay" or "Cabernet Sauvignon" or "Merlot" or so on.

Wine Regions of the World
Basic Wine Term Pronunciation
World Vineyard Planting Acreage