Portugal has a long tradition of winemaking with the vines most likely being introduced by the Phoenicians and later developed by the Romans. And by the XVth century a history of exporting had being established.
Portugal established its international reputation early on with the production of two famous styles of fortified wine, Maderia from the island of the same name off the coast and Port from the Douro valley.
However don't compare Madeira with Port. While both are fortified wines there production is very different. Madeira, during vinification, undergoes a process known as estufagem. This is a slow heating process, which, amongst other things, caramelizes the wine's sugars and gives Madeira its unique flavor. Sherry is probably a better comparison.
Today Port is the better know fortified wine of Portugal. Adding pure grape spirit to the wine after about half the sugar has been fermented into alcohol produces it. The spirit inhibits any further fermentation thus creating a slightly sweet wine with approximately 20% alcohol. A similar process is used for Madeira. Though drier wines such as Sercial are fermented longer, converting more of the sugar into alcohol and leaving less residual sugar.
Port wines range from ruby port, which are normally medium bodied with and average age of three years to vintage port, which is produced, only in exceptional vintages. It will spend 2 to 3 years in cask, and normally requires 15- 20 years maturation in bottle before drinking.
While Portugal’s reputation for fortified wines was legend the production of table wine lagged behind. The wines in fact until about 20 years ago were produced in a very traditional style e.g. made for the Portuguese taste. Since then the vineyards, vinification, packaging and trade methodology, have been bought into line with the modern world of wine. As a result the wines are quite different, wineries now take advantage of the high-tech revolution to producing wines to suit the international taste, even with the use of native grapes variety. Today Portuguese wines represent reliable, excellent price quality ratios wines for the consumer.