Balsamic when made in the traditional way is an outstanding vinegar. It is dark in color, very smooth and mellow with deep complexity and layers of subtle flavors. The very finest Balsamics are made from the the juice of Trebbiano grapes that has been boiled down to almost a syrup. This reduction goes through a first natural fermentation in wooden casks that produces alcohol. A second fermentation, with the aid of the acetobacter bacteria in the air, creates the acetic acid that is vinegar.
This vinegar is then filtered into wooden casks and left to mature for anywhere from 10 to 30 years. Some for even longer. Some Balsamics mature in a succession of casks all made from a different type of wood, each type giving a another layer of flavor to the vinegar. It is this almost magical combination of wood, wine and time that makes traditionally made Balsamic vinegar such a rare and very expensive delight.
Historically , Balsamic vinegar originated in Modena; a town in northern Italy. Commercially made Balsamic vinegar is made in the region as well and while nowhere near the quality of the traditionally made vinegar, it is very good and markedly different from other wine vinegars.
Though produced on a large scale , most commercial Balsamics are left to mature in wood for varying lengths of time and develop the basic characteristics of the traditionally made vinegar.