Saint-Émilion wines are predominantly made from Merlot and Cabernet Franc. The other traditional Bordeaux varieties (Cabernet Sauvignon, Carmenere, Petit Verdot and Malbec) are permitted for use here, but are rarely used to any significant extent. This is not so much a question of taste and style as one of terroir; the clay and chalk rich soils around Saint-Émilion are generally cooler than those on the Médoc peninsula, and are less capable of ripening Cabernet Sauvignon reliably. Merlot makes up around two thirds of vines planted around Saint-Émilion, and continues to increase in popularity because of the softer, more approachable wine styles it produces. There are two notable exceptions to this: Château Cheval Blanc, where Cabernet Franc occupies 58 percent of the vineyard area, and Château Figeac, where Merlot, Cabernet Franc and (more unusually) Cabernet Sauvignon enjoy equal representation in both vineyard and wine.
Geologically speaking, Saint-Émilion can be divided into three main vineyard areas. The most significant is the limestone plateau on which Saint-Émilion town is located, and the slopes around it. Most of the very top vineyards and châteaux are located here, within a mile of the town (Cheval Blanc and Figeac again provide two notable exceptions to the rule).
Immediately south of the limestone plateau is the alluvial, sandy plain which slopes gently down to the banks of the Dordogne. Few wines of any note are produced here, and none of the Grand Cru Classe properties are located here.
Saint-Émilion has four satellite areas: Lussac-Saint-Émilion, Saint-Georges-Saint-Émilion, Puisseguin-Saint-Émilion and Montagne-Saint-Émilion. These cover distinct, slightly smaller areas immediately northeast of Saint-Émilion proper, and each has its own independent appellation title.
Saint-Émilion also has a Grand Cru appellation (Saint-Émilion Grand Cru), which imposes slightly tighter production restrictions. This has been the subject of much criticism since its introduction in 1954, as the restrictions are widely viewed as being too loose to warrant the use of the Grand Cru title, and twice as much Saint-Émilion Grand Cru wine is made each year than regular Saint-Émilion.
Fortunately, the Saint-Émilion Wine Classification system performs the task of marking out the area's top-tier wines. This works in much the same as the classifications of the Médoc, Graves and Sauternes, but with one significant difference: it is periodically reviewed to keep it up-to-date and relevant. It was first drawn up in 1955, and (after a controversial review in 2006) was most recently updated in 2012.