Bordeaux is comprised of 57 regions of which 4 stand out: Medoc, Graves, Pomerol and St-Emilion.
Medoc wines are typically 60% Cabernet Sauvignon, 25% Merlot and 15% Cabernet Franc. In 1855 the 61 Chateaux of Medoc were classified in 5 Grand Cru Classes (Growths) according to its reputation. Today an additional 247 Chateaux are classified Crus Bourgeois.
Graves' 16 Chateaux were rated 100 years later in 1959. Unlike the other 4 regions White wine is also produced along with great Reds.
Pomerol wines typically are 95% Merlot and tend to be softer, fruitier and ready to drink sooner. Pomerol produces about 10% as the Medoc region and thus tend to be scarcer and more expensive. The chateaux are not classified.
St-Emilion wines are typically 70% Merlot, 25% Cabernet Franc and 5% Cabernet Sauvignon. In 1955 its 61 Chateaux were originally classified representing about two-thirds of Medoc production.