Port is one of the most regulated wines made today. The production area was also the first to be so demarcated in 1756. Vineyards are graded by the Instituto do Vinho do Porto (IVP) according and classified into six different categories labeled "A" through "F". There are twelve different physical factors taken into consideration including productivity (the lower the yield, the higher the mark), gradient, aspect, soil, exposure, and vine varieties. Each factor is given a numerical value which is then tallied up. A score of more than 1200 points out of a maximum 1680 points is given an "A". Vineyards scoring less than 200 points are given an "F". As only a certain amount of wine is allowed to be made into Port in any given year, growers are allowed to make a certain amount of Port from their particular vineyards based on the grade they receive. A vineyard with an "A" grade are allowed to make up to 600 liters of Port per 1000 vines. Those with a grade of "F" generally have to pass on the Port market. Surplus grapes are usually made into table wine.

There are over 90 different varieties of grape permitted to be grown in the Port wine region. Of these, about 30 different varieties can be found there, but only 5 are considered to be of exceptional quality. These are Touriga Nacional, Tinta Roriz, Tinta Barroca, Tinto Cão, and Touriga Francesa. White Port, is made from white grapes rather than the aforementioned red grapes — Viosinho, Malvasia Fina, Gouveio, Cédega, and Rabigato.

The Touriga Nacional grape is said to be without a doubt, the best grape for making Port. It is not however, the most widely planted variety. It is a vigorous and robust vine, but produces about half the yield as the other grape varieties. This grape gives Port its deep color and longevity.

There are many styles of Port, but two broad categories define Port – bottle aged or cask aged. The two processes produce distinctly different wines. Bottle aged Ports keep their color and generally their fruitiness into their maturity They are aged for a short time in wood and are bottled without filtration where they are meant to mature. Cask aged Ports lose much of their and become tawny in color. These are aged in wood and then filtered and bottled. They are ready to drink right away.

Tawny is aged a few years longer than ruby – at least six years – in the cask before it is bottled. Though some tawny is simply a mixture of ruby and white ports, the best tawny Ports have acquired their pale color – an amber brown or tawny hue – from longer wood ageing. The flavor becomes drier and nuttier from the oxidation.

Vintage Character Ports might also be referred to as Super or Premium Ruby. It is a blend that has been aged from four to six years before it is filtered and bottled. They characteristically have more body and fruit than a tawny but they lack the concentration and complexity of a true vintage Port. These are usually marketed under brand names like Sandeman's Founders Reserve, Warre's Warrior, Graham's 6 Grapes, Fonseca's Bin 27, and Taylor's First Estate.

Aged Tawny are the best tawny Ports. They give the average age of the wines that have gone into making the blends. They are available in 10, 20, 30 and 40 year versions with a corresponding increase in price. A 20-year tawny may give you the most enjoyable experience for the price. Aged tawnies are made from high quality wines and are the byproduct of a master blender.

Ruby is the most basic and least expensive style of Port. It is a blend from the produce of several harvests, that spends two to three years in stainless steel or wood before it is bottled. You usually will not see the term Ruby on the label as most shippers prefer to use a house brand. 

Vintage Port if the finest and most expensive of the Port styles. At most, it accounts for about 2% of all production and is one of the most sought after wines in the world. Vintage Port comes from a single harvest of exceptional quality, as stated on the bottle, and is bottled after two to three years of cask ageing. The wine then spends many years maturing in the bottle. It may take 15 to 50 years for a good Vintage Port to be ready for drinking. Each shipper must decided within two years of a harvest year if that particular year will be of enough quality to be released as a Vintage Port. This is known as "declaring the vintage". The first vintages were declared around 1734. The best vintages from this century include 1994. 1992, 1991, 1985, 1977, 1970, 1963, 1955, 1948, 1945, 1935, 1931, 1927, and 1912. These wines must be decanted before serving. This is not as difficult as it may sound. See the section on Serving and Storing Port . 
 
White Ports range from very dry to very sweet. The sweetest is designated as Lagrima. These are served straight up or on the rocks, most often as an apéeritif.

Colheita is a tawny but from a single vintage. It might be though of as a vintage tawny. It must receive a minimum of seven years in wood, but most are aged much longer. Also the wine should indicate the year of bottling and should be drunk within a year of that date. This is the rarest of all Port. Their production, a specialty of the Portuguese Port houses, amounts to less than 0.5% of all Port made. 
 
Crusted Port is named for the crust of sediment it forms in the bottle. It is a blend of port from several vintages that is bottled after three years in cask.

Single-Quinta Ports are made in both tawny and vintage styles but with the distinction that they come from only one vineyard. They are generally produced in years that are not declared. In declared years, their grapes often form the backbone of the Vintage Port blends. 

Late Bottled Vintage or LBV, unlike Vintage Character, are actually the produce of a single vintage. A vintage not deemed good enough to make a Vintage Port, will go into the making of a LBV. It is left in wood for four to six years, then fined and filtered before bottling. It is ready to drink earlier than Vintage Port and they do throw little sediment in the bottle.