Sweet wines come in many shapes and forms, from different grape varieties and different wine making styles. "Late Harvest" wines come from grapes are left in the vineyard into autumn to develop further sweetness and shrivel on the vine.  'Noble' when Botrytis wines come from a mold growing on the grapes sucks water from the fruit and leaving behind highly concentrated juice. Others are fortified during the winemaking process by adding alcohol, stopping the ferment and leaving behind natural fruit sugars.