The structure of wine rests on five key components: acidity, tannin, alcohol, sugar, and body. Tannins are compounds that create the astringent, drying sensation found predominantly in red wines, sourced from grape skins and seeds and supplemented by oak aging. Body describes the perceived weight of wine in the mouth, ranging from light to medium to full, influenced by alcohol level, glycerol content, and other components. Acidity provides the crisp, tart quality that balances sugar and body, contributing to a sense of freshness and longevity. Residual sugar refers to the sugar remaining after fermentation and determines whether a wine tastes dry, off-dry, or noticeably sweet. Together, these elements create a wine's balance when they harmonize without any single component dominating, and a satisfying finish when flavors linger pleasantly after swallowing—a quality known as length or finish, often considered a hallmark of fine wine.
Beyond structure, winemaking techniques profoundly shape a wine's character and style. Oak aging adds flavors of vanilla, spice, and toast while softening tannins through micro-oxygenation. American oak tends to deliver bolder vanilla and coconut notes, while French oak contributes more subtle spice and fine-grained structure. Malolactic fermentation is a bacterial conversion of malic acid into the softer lactic acid, creating the buttery, creamy quality found in many Chardonnays and softening high-acid reds. Bâtonnage, the practice of stirring wine on its lees (the spent yeast cells that settle after fermentation), adds creamy texture and complexity during aging and is characteristic of certain white wine styles.
Several distinctive winemaking approaches define entire wine categories. Sparkling wines gain their effervescence through a secondary fermentation; the méthode champenoise performs this in the bottle, producing Champagne's signature fine bubbles and toasty autolytic character, while Prosecco uses the Charmat tank method for fresher, fruitier wines and Cava employs the traditional bottle method in Spain. Rosé wines are made from red grapes with limited skin contact, producing everything from the pale, bone-dry rosés of Provence to the richer, sweeter White Zinfandel style popular in the United States. Fortified wines achieve their distinctive character by adding grape spirits; Port is fortified during fermentation to preserve sweetness, Sherry undergoes a unique solera aging system in Jerez, Madeira is heated during production to create its oxidized style, and Marsala is fortified in Sicily, each reflecting centuries of regional tradition.
Sweet wine production includes some of the most labor-intensive techniques in winemaking. Icewine, known as Eiswein in German, is produced from grapes left on the vine until they freeze, concentrating sugars dramatically when pressed while water remains as ice. Botrytis cinerea, sometimes called noble rot, is a beneficial mold that dehydrates grapes on the vine, concentrating sugars and producing the legendary sweet wines of Sauternes in Bordeaux and Tokaji Aszú in Hungary. Modern winemaking also embraces various philosophies: biodynamic wine follows Rudolf Steiner's holistic farming principles, treating the vineyard as a unified organism; organic wine uses certified organic farming practices; and natural wine is a movement emphasizing minimal intervention in both vineyard and cellar, including limited sulfite use—though sulfites, which occur naturally in small amounts and are added to most wines as a preservative, remain a standard tool for protecting wine from oxidation and spoilage.