Wine is silly fermented grape juice. The natural yeasts on the grape skins convert the sugar in the juice to alcohol. The basic chemistry is simple, but making fine, complex wine is far more involved and there are significant differences in how wines are made when different styles are the goal. These involve such basics as the ripeness of the grapes when harvested, whether the wine undergoes a secondary fermentation called malolactic fermentation, and whether the young wine is aged in new or used oak barrels and for how long, or whether it is aged in oak at all.
The notion of fine wine begins with the most basic decision: what kind of grapes to grow and where to plant them. Great wines start in the vineyard. Factors that influence a vine’s health include the soil’s texture, drainage, depth and color. Areas which receive lots of rainfall benefit from rocky soils that drain easily. Cool areas benefit from soils that collect and hold heat. Exposures influence how much or how little sun a vine receives; a north-facing vineyard. All of these factors are taken into consideration when producing high quality wines.
While some grape varieties will flourish in a wide variety of soils and climates, the fine wine grapes need fairly specific soils and climates, the fine wine grapes need fairly specific soils and climatic conditions to excel. When grape and soil are properly matched, the resulting wines reflect the place where they are grown, what the French call terroir. Terroir expresses the interaction of many factors with the grapevines, temperatures by day and night, rainfall distribution by season and year exposure to sun, soil acidity, soil depth, soil composition, and proximity to body of water
-basically anything natural that influences the growth of a vine. This is perhaps the most important trend in wine growing today- matching the right grape to the right soil and climate.