To know what Sherry wine is you have to understand what a fortified wine is. To transform a regular wine into a fortified wine grape spirits or Brandy is added to the fermenting juice to stop sugars at a certain point from converting to alcohol. Sherry is one of those wines where grape spirits is added to stop this process. After the Sherry achieves its proper alcohol levels it is tested for quality and separated into two types of Sherry: Fino and Oloroso. Each of these types of Sherry have further classifications.