Balsamic vinegar is a dark, concentrated, intensely flavored vinegar originating in Italy. It is made wholly or partially from grape “must“ (juice extracted from grapes crushed along with the skins, seeds and stems).

In Modena, a city in northern Italy’s Emilia-Romagna region, balsamic vinegar is more than just a condiment or salad dressing; it’s a way of life, and has been for nearly a thousand years. Traditional Italian Balsamic must be produced in Modena or in the neighboring city of Reggio Emilia.

Modena’s claim to balsamic fame starts with a “must” of white Trebbiano grapes, which is boiled down until it is 1/3-1/2 of the original volume. The liquid is poured into barrels that have been pre-rinsed with boiling vinegar, then it is left to age for a year.

At the end of the year, the now-syrupy liquid is put in wooden kegs. After another year, when the aging has further reduced and thickened the vinegar, it’s put into even smaller wooden barrels, and so on every year. The flavor intensifies over the years, with the varieties of wood used giving the vinegar its particular taste and character.

Each producer has their own secret combination of aging techniques to achieve a particular texture, flavor, and aroma, but true balsamic is always rich, glossy, and deep brown, with a flavor that balances the sweet and sour elements of the grape with that of the wood.

Balsamic vinegar is aged from 10 to 25 years; and just as with fine wines, the price appreciates with age.

More Info: en.m.wikipedia.org