Business card, advertising hoarding and legal statement: a wine label is all three of these things. It tells you a lot - in some cases far too much - about the liquid you are going to taste, drink or, on occasion, spit out. A label will give you information about a wine's origin, its alcoholic degree, its vintage (assuming it is the product of a single year rather than a blend of harvests), the name of the producer and, in the New World at least, the grape variety or varieties from which it was made.
What it won't tell you about, alas, is the quality of the wine in the bottle. European countries have established a nominal hierarchy for their wines, but this is a guide, not a guarantee. There are plenty of vins de pays that taste better than supposedly superior appellation contrôlée wines, just as there are Italian vini da tavola (table wines) that outperform and outsell wines from denominazione di origine controllata (DOC) areas.
The most important thing to look for on a label is the producer's name, especially in a region like Burgundy where dozens of growers may own vines in the same vineyard. (The 50 hectares of the Clos de Vougeot Grand Cru are famously divided between more than 80 different owners). Having a producer whose wines you trust is a godsend in a restaurant when you're confronted by a list of unfamiliar names.
The second most important thing on a label is the name of the grape variety, or varieties, from which the wine was made. Many European appellation areas do not allow these to be listed on the front label, though they are increasingly mentioned on back labels. New World countries, on the other hand, have built their success on so-called 'varietalism'. Where would California be without Chardonnay or Australia without Shiraz?
Grape varieties mutate from country to country, but they retain a family resemblance. If you like the aromas, flavours and structure of, say, Cabernet Sauvignon in Chile, you will probably enjoy examples from France, California, Italy and Bulgaria too. Not all wines are made from single varieties, of course, but it's worth discovering the identity of the dominant grape in your favourite (blended) wine style so that you can seek it out in isolation.
The other thing to look out for on a label is the vintage. (I'm less interested in alcoholic content, although wines can vary in strength from around 5 per cent to over 20 per cent.) There's nothing more annoying than seeing dual vintages on a wine list. In cooler and more marginal areas where harvests vary considerably from one year to the next, the vintage is a vital piece of information. To take only one example: 1996 was a much, much better year in Bordeaux than 1997, although, as ever, good producers managed to make very drinkable wines in the latter vintage. In the New World, vintages are less important than in the Old, especially in warm, sunny areas such as the Barossa or Central Valleys, but even here things are not as consistent as producers would have you believe.
Very few vintages are good everywhere, although with the exception of the Douro Valley, where a vintage year was not declared, 1990 produced very good to outstanding wines in most parts of the winemaking world. More recently, 1995 was a pretty consistent year. Naturally, this applies to fine rather than everyday wines. Where the latter are concerned, only one piece of vintage advice matters: the younger the better.