 The sweetness of wines is determined by the amount of residual sugar left in the wine after the fermentation process.Wines can be bone dry (with the sugars fully fermented into alcohol), off-dry (with a hint of sweetness), semi-dry (medium-sweet) and dessert level sweetness (such as the high sugar content in Sauternes and Tokays).Sweet wines often need to be sweeter than the dish they are served with.