Port wine be labelled as "port" or "Porto". In the United States, wines labelled "port" may come from anywhere in the world, while the names "Oporto", "Porto", and "Vinho do Porto" have been recognized as foreign, non-generic names for port wines originating in Portugal. Port is produced from grapes grown and processed in the demarcated Douro region. The wine produced is then fortified by the addition of a neutral grape spirit known as aguardente in order to stop the fermentation, leaving residual sugar in the wine, and to boost the alcohol content. The fortification spirit is sometimes referred to as brandy but
Madeira wine up large (112 gal/423 l) casks of wine known as "pipes" for their voyages to India. The intense heat in the holds of the ships had a transforming effect on the wine, as discovered by Madeira producers when one shipment was returned to the island after a long trip. The customer was found to prefer the taste of this style of wine, and Madeira labeled as "vinho da roda" (wines that have made a round trip) became very popular. Madeira producers found that aging the wine on long sea voyages was very costly, so began to develop methods on the