Vinegar may figure prominently in nouvelle cuisine but it is far from new. In fact, vinegar is one of the world's oldest products, discovered thousands of years ago when some wine, left out too long, went sour. Hence, its name; in French, it means "soured wine."

In some respects, vinegar can be considered the ultimate in recycling -- it makes good a product that has gone bad. The base may be wine, grain, rice, molasses, fruit, honey or even coconut that has undergone two fermentation processes. The first turns natural sugars into alcohol, the second turns the alcohol into acetic acid, the main component of vinegar.

The level of acidity is usually noted on bottles in one of three ways. It may say "6%", "6 " or "60 grain" on a bottle of red wine vinegar, indicating it has a 6 percent acidity level. The levels of vinegar on sale today vary from 4 to 8 percent; the higher the number, the greater the acidity. Even so, an 8-percent vinegar may not be more tart if that vinegar has been aged slowly in wood containers, which produces a more mellow taste than vinegar made faster by more modern technology.

To find the vinegar that suits your taste, bypass the label and instead test the taste. If possible, buy a small bottle and taste over either lettuce or bread. Also, smell. If it's an herb vinegar and you can't smell or distinguish the herb, it is probably not worth buying again.

Nor do you need to buy one of every flavor. Some can be used interchangeably, so figure out which ones you are likely to use and buy just a few.

Here is a rundown on the different flavors:

Distilled white vinegar, made from corn, rye and other grains, is clear and very pungent, the cheapest form of vinegar, used primarily as a pickling agent.

Apple cider vinegar is, of course, made from apples. Used for pickling and in salads and stews, it can be used interchangeably with wine vinegar in most poultry and meat dishes, but not in fish dishes.

Wine vinegar varies greatly in pungency. Champagne vinegar is very mild and works well in light salads; sherry vinegar is heavier, producing a full flavor in soups, stews and hearty salads. Red and white wine vinegars can be used in almost any dish -- and interchangeably -- unless it's a white sauce in which red wine vinegar could ruin the color.

Balsamic vinegar, made in and around Modena, Italy, is valued for its fruity and woody taste. Unfermented juice, or must, of the Trebbiano grape is boiled down to a sweet syrup that is aged in wooden barrels.

True balsamic vinegar is aged for several years and costs as much as $100 or more a pint. What most Americans buy is a commercial version in which wine vinegar is used as the base, then cut with must. The more must used, the better the quality (and usually the higher the price).

Because of its intense taste, very little balsamic vinegar is needed to impart its flavor. It is great in almost any dish, including with fruits.

Malt vinegar, made from barley, is very pungent and has a heavy body, making it perfect for the English meal of fish and chips.

Rice vinegar, used in Oriental cooking, is one of the lightest, cleanest vinegars available. It goes well on light salads and dishes where a pungent taste of vinegar would be overwhelming.

Fruit and herb vinegars are made by steeping fruits or herbs in vinegar, usually wine vinegar. The fruit vinegars are nice on salads, chickens and game. A dash in club soda also makes a refreshing summer drink.

Herb vinegars go well in salads, stews, soups and marinades -- especially in winter when a good herb vinegar imparts a sharper and fresher taste than most of the fresh herbs available in the supermarkets.