The Saint-Emilion Classification system identifies French wines using several different factors. The region in which the grapes are grown is the primary basis for the classification. This system was initiated in 1954 and is updated on a (roughly) ten year schedule.
Currently, there are several different ways to classify French wines but the French government has instituted this system based on Appellation d'Origine Contrôlée (A.O.C.). This system is part of French law.