A vintage wine simply means which year the grapes were grown and harvested. You can see the year the wine was created on the labels on the bottles. And that they originate from a single vintage.
However, there are some wines that are considered as non-vintage, fortified and sparkling wines. The most common non-vintage wine is champagne, and is simply labeled as “N.V.” These wines are regularly created from different vintages to create a consistent style of wine and in good value. In both cases, the producer will decide when to declare a good single vintage wine.
The wine's taste and quality depend on the wine's vintage primarily due to the weather that greatly affects the grapes during the course of the growing season. The grape growing season in Northern Hemisphere or North America and Europe is from April to October. In Southern Hemisphere or in Argentina, New Zealand, and other countries, the growing season is from October to April.
A good vintage wine depends on the quality of grapes produced. If the region has more sunny days, the grapes have the best chance to reach full maturity and optimum ripeness levels. In some regions, if they produce great vintage red wines, it doesn't mean that they also produce white wine wines. However, if the region is too hot and several sunny days above 92 ºF / 33 ºC, the grapes tend to raisinate before they reach full maturity, and this will result to flabbiness or bitter tannins in wines.
A bad wine vintage is a result of lower quality of grapes. If the region where the grapes originated receives more rain and clouds, the grapes don't reach full maturity or ripeness. They are more prone to rot and diseases, so they deliver a lower quality of grapes.
Take note: Different types of grapes require different types of climates. For instance, Riesling nurtures well in sunny regions with cool nights, while Cabernet Sauvignon grows well in a region with a dry, hot and sunny climate.
"Wines improve with age", is a well-known wine saying, but not all aged wines are fine ones and some of the best wines are not old. The taste depends on the weather where the grapes are grown. In the wine world, "vintage" means, the age of the wine. If you want to learn more about the wine you're enjoying, hopes this gives you a heads up! Cheers!