Port wine (also known as Vinho do Porto, Oporto, Porto, and Port) is a sweet Portuguese, fortified wine from the Douro Valley in the northern provinces of Portugal. It is often served as a dessert wine. Wines in the style of the Portuguese product called Port are produced around the world in several countries - most notably Australia, South Africa, India, Canada and the USA. However, under European Union guidelines (and Canada), only the wine product from Portugal may be labeled as Port. In the USA, Federal law mandates that the Portuguese-made product be labeled Porto or Vinho do Porto.
Port is produced from grapes grown and processed in the Douro region. The wine produced is then fortified with the addition of distilled grape spirits in order to stop the fermentation leaving some rest sugar in the wine and to boost the alcohol content.

 

The wine is then stored and aged; often in barrels stored in caves (Portuguese meaning "cellars"), before being bottled.
The wine received its name, 'Port,' in the latter half of the 17th century from the seaport city of Porto at the mouth of the Douro River, where much of the product was brought to market or for export to other countries in Europe from the Leixoes docks. The Douro valley where Port wine is produced was defined and established as a protected region or appellation in 1756 - making it the second oldest defined and protected wine region in the world.

STYLES OF PORT:

White Port: After fermentation white port is aged for a short time in neutral oak casks or stainless stank tanks and then bottled. The taste can vary from dry to very sweet in flavour.
Ruby Port: Ruby port is aged up to 2 years in large oak vats prior to being bottled. It has a rich red colour and a full fruity taste.
Tawny Port (and Aged Tawny): Tawny port is aged for a minimum of 2 years in the smaller oak casks and then bottled. It has a deep mahogany colour and a drier wine with a nuttier taste. Aged tawny port is usually aged for 10, 20 or 30 years but some of the more expensive ones have been aged for more than 40 years.
Crusted Port: Crusted port is a ruby port that is aged for about 3 years in cask and then finishes the aging process in the bottle. It is a blend of grapes from several different years and it is not filtered before being bottled which is why it will have sediment in the bottle.
Late-Bottled Vintage (LBV): Over time it has become two distinct styles of wine, both of them bottled between 4-6 years after the vintage, but one style is fined and filtered before bottling, while the other is not.
Reserve Port or Vintage Character: Reserve port is a premium ruby port - it has no single vintage (usually being a blend of several vintages 6-8 years of age of ruby port) nor the typical character of vintage port.
Vintage Port: Vintage port is aged in barrels for a maximum of two and a half years prior to being bottled and then it is allowed to age for ten to forty years in the bottle. It is one of the most sought after wines in the world and also one of the most expensive.

Grapes used to make Port:
Red Port can be made from many types of grapes, but the main ones are Tinta Barroca, Tinta Cão, Tinta Roriz (Tempranillo), Touriga Francesa (Touriga Franca), and Touriga Nacional. White Ports are produced the same way as red Ports, except that they use white grapes - Esgana-Cao, Folgasao, Malvasia, Rabigato, Verdelho, and Viosinho.