Most wines, even those that are designated by a particular varietal type such as Cabernet Sauvignon, are actually blends of different grape varietals. The rules vary on what percentage of a particular varietal must be present in a wine for it to be labeled as that varietal. In the United States the general rule is 75%. Thus, a wine designated as a Cabernet Sauvignon must be comprised of at least 75% Cabernet Sauvignon juice.

At times, a winemaker will produce wines that do not meet these criteria in order to develop a specific flavor profile. These wines will often be named with the primary varietals that make up the blend, such as Cabernet-Merlot. Typically, the the varietals designated are listed in order of decreasing proportion.

Meritage or Claret are two common names that may be used to label wine comprised of a blend of grapes. These two names in particular are reserved for blends of the Bordeaux varietals. Some wineries even create proprietary names for their blends. Franciscan Winery's Magnificat is an example of such a wine. Opus One is a California winery that is solely dedicated to producing a single, proprietary, red blend in the Bordeaux style that simply carries the name of the winery.

In Italy, France, and Spain, it is common for wines to be labeled for the region in which they are produced. As such, we have become familiar with styles such as Chianti, Bordeaux, and Rioja. There are usually legal restrictions on the grape varietals that can be grown and used for the production of such wines.