Bordeaux is the region of France, along with Burgundy, that most fine wine drinkers gravitate towards. The reds are almost always a blend of anything up to 6 black varieties: Merlot, Cabernet Sauvignon, Cabernet Franc, Malbec, Petit Verdot and Carmenere. Depending on what part of Bordeaux you are in determines which of these varieties dominates, but largely speaking, Merlot is generally the number one.
The heartland of the Cabernets is the Medoc, the left bank of the Gironde Estuary, which is sub-divided into communes and AOCs, the most famous of which are (north to south) St Estephe, Pauillac, St Julien and Margaux. Among these 4 communes are where the Grands Crus of the Medoc 1855 Classification are to be found, but there are other AOCs where you can find less expensive wines such as Haut Medoc, Listrac-Medoc and Moulis.
To the south of the city of Bordeaux you can find the Graves, Pessac-Leognan and Sauternes AOCs, the latter of which is for sweet white wines whilst the former two are known for both reds and dry whites, normally from a blend of Sauvignon Blanc and Semillon with a smattering of other minor varieties.
The right bank of the estuary is Merlot territory. This is where you will find St Emilion, with all its satellite villages, and Pomerol, the latter being the centre of gravity for Merlot-based wines. However, the most important vineyard of all is the Entré deux Mers - between the seas, or rivers in this case - where the bulk of Bordeaux's wines hail from, many of which are simply labelled as Bordeaux or Bordeaux Superieur, and Bordeaux Blanc Sec or Entré deux Mers for its whites