I originally wrote this post for Chowhound's Wine Board more than five years ago. I'm re-posting it in its own thread for the following reasons: a) it seems to have been helpful for several people; b) I've corrected/added a few things; and c) it's very difficult for me to find and refer people to. Hope everyone (and the Mods) don't mind.
There are many ways to categorize Porto . . . one version of an outline (hard to do when you can't use tabs) of Porto would look something like this. Keep in mind, by the way, that there are many different ways to do this outline; also, this applies only to real (i.e.: Portuguese) Porto.
1. Ruby Porto (defined as red Porto wines bottled with less than seven years of wood aging).
1a. No indication of age.
1a1. True Ruby Porto, bottled very young.
1a2. Vintage Character Porto (a fuller, "beefier" style of Ruby Porto).
1a3. Crusted Porto (a non-vintage blend of between four-and-six years of age).
1b. Ruby Ports with a Vintage date.
1b1. Late Bottled Vintage Porto (by law, bottled between 4-6 years of vintage -- note, numbers here are rounded off).
1b1a. Traditional, unfined, unfiltered (this will improve with further bottle aging).
1b1b. "Regular" (fined and/or filtered; generally doesn't improve with bottle age).
1b2. Vintage Porto.
1b2a. True Vintage Porto (a producer's "main," showcase product -- by law, bottled two years after vintage [again, rounded] and capable of great improvement with added bottle age).
1b2b. Single-quinta Vintage Porto (either from a small, estate, or from a large producer, but made from a single estate; again, bottled two years after vintage [again, rounded] and capable of great improvement with added bottle age).
2. Tawny Porto -- red Porto wines bottled with 7+ years of wood aging.
2a. No indication of age.
2a1. Young Tawny (often a mix of Ruby and Tawny).
2a2. True Tawny Porto.
2a3. Tawny Reserva, a usually branded bottling of Tawny Porto that is "older" than the "true" Tawny Porto.
2b. With a general indication of age.
2b1. 10-Year Tawny Porto.
2b2. 20-Year Tawny Porto.
2b3. 30-Year Tawny Porto.
2b4. 40-Year Tawny Porto.
2c. With a specific indication of age.
2c1. Colheita Porto.
2c2. Garrafeira Porto.
3. White Porto.
3a. Bottled young.
3a1. Very Dry.
3a2. "Dry" (in reality, off-dry).
3b. Bottled after 7+ years of wood aging.
3c. With a specific indication of age.
3c1. Colheita Porto.
3c2. Garrafeira Porto.
4. Pink Porto.
4a. Bottled young, off-dry, served chilled or in cocktails.
* * * * *
All of the Porto listed under "1b. Ruby Ports with a Vintage date" will carry TWO dates on the label. The date in the largest print will be the calendar year in which the grapes were harvested -- in other words, the vintage date. The second date, appearing in *much* smaller print, will be the year of bottling. So a *true* Vintage Porto will say "2011 Vintage Porto" (big print), followed by "Bottled in 2013" (small print). A label of Late Bottled Vintage Porto would similarly read "2009 LBV" (big print), and "Bottled in 2014" (small).
Colheitas (2c1) and Garrafeiras (2c2) are from a single year's harvest, but are NOT Vintage Porto -- even though no wine from another year was blended into it. These age for at least 7 years in wood, and will also carry *both* the calendar year of harvest and the calendar year of bottling on the bottle. Thus you could have (for example) a 1981 Colheita bottled in 1988 -- but you could also have a 1981 Colheita bottled in 1994 or in 2007 or in 2015 . . . .