Late harvest wines, wines produced from noble rot infected grapes, and fortified wines are three of the most common styles of dessert wines available on the kosher market.
Late Harvest Wines: This style of dessert wine is produced by harvesting the grapes late in the season. This allows the sugar levels in the grapes to accumulate. Grapes that are commonly used to make this style of dessert wine are Riesling, Gewurztraminer, Sauvignon Blanc and Zinfandel.
Noble Rot: A fungal disease, also known as Botrytis Cinerea, that can produce some of the finest sweet wines of the world. Botrytis infected grapes are used to make French Sauternes and Hungarian Tokaj.
Fortification: This is the practice of adding spirits, usually grape brandy, to a wine to stop fermentation before all the sugar is converted to alcohol. The brandy also raises the alcohol content of the beverage. Port, Madeira, Sherry, Marsala, Liquer Muscat, and Vin Doux Naturel are all made using this tenchnique.