Chablis is the northernmost subregion of Burgundy. It is a very cool climate area, often exposed to spring frosts, which is countered by spraying water on the vines that will freeze, forming a protective coating around the buds. Another technique is the use of smudge pots to heat the air in the vineyards.
The vines are planted on well-exposed hillsides on a soil of Kimmeridgian clay. This special type of soil contains a high percentage of marine fossils, giving the vine a lot of calcium which builds structure in the soil and imparts a mineral character to the wines produced. The vineyard area was expanded in the 1990s to include some parcels on Portlandian clay, which is not as ideal. Previously, the land in this expanded area had been relegated to the lesser appellation Petit Chablis, along with those sites with northern exposure.
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The style of the best Chablis shows a citrus/green apple fruit character on the nose with a pronounced minerality. On the palate it is dry, with crisp acidity, but showing a richness on the palate that comes from Chardonnay produced from great terroir. 
There are 17 Premier Cru vineyards scattered throughout Chablis, although some are falling into disuse. Fourchaume and Montmains are among the best-known and the most highly regarded, along with Montée de Tonnerre and Vaillons. These wines show greater concentration and more depth of flavor than AC Chablis.