Fortified wines are those to which spirit alcohol has been added at some stage of production, generally to stop fermentation (the rise in alcohol killing the yeast) to leave a proportion of unfermented sugar in the wine. The best known examples, namely port, madeira, and marsala, were created by British traders wanting to stabilise wine and ensure it landed in good condition at its destination. Sherry differs from the others in that spirit is added after fermentation; sherry is made in a wealth of different styles and sweetness levels.
