Fortified wines were created in the 16th-17th centuries when brandy was added to wines to stabilize them for long sea voyages, as many wines would spoil. This allowed the wines to better withstand temperature fluctuations and led to new styles of fortified wines like Port, Sherry, Madeira, Marsala, Malaga and Montilla becoming popular at destinations. These wines contain 17-21% alcohol making them more stable once opened than table wines.