Balsamic vinegar is a traditional thick flavoured vinegar commonly used in Italian cuisine. It is also often used as a salad dressing when combined with oil. It is a traditional product originating in Modena, where it has been made since the Middle Ages and the name is protected by the Italian government. Unlike common vinegars, it is dark and thick with a complex, sweet taste and is much more expensive.

Balsamic vinegar is a very dark-colored vinegar with a somewhat sweet flavor; in its long-aged forms (at least 10 and even up to 25 years) it is often taken straight or served over strawberries, while the more mass-market vinegar (usually aged 3 years or less) is used in salad dressings and marinades.

It is produced from the concentrated juice ("must") of white grapes (typically, trebbiano grapes) that has been boiled down to approximately 50%, and fermenting that into alcohol. This is then once again fermented to balsamic vinegar, with a slow aging process that concentrates the flavours. The flavour is intensified over decades, with the vinegar being kept in fine wooden casks, becoming sweet, viscous and very concentrated in flavour. The finest and most traditional balsamic vinegar is very labor-intensive to produce; while it ages and gradually evaporates, the liquid is transferred to successively smaller casks made of different woods, absorbing the flavor characteristics of each wood and becoming more concentrated with each transfer. Oak, mulberry, chestnut, cherry, juniper, and ash are the most commonly used woods. Some older balsamic vinegar is added to the "must" to create a more complex and intricate taste, and to add acidity.

Balsamic vinegar of the highest quality, labeled tradizionale, usually sells for very high prices; a small (100 ml) bottle can cost between US $100 and $400. Most producers, however, do not employ all six of the aforementioned woods in the aging process; some employ only oak. Several mass-produced, less expensive varieties may not be aged in wood at all, being nothing more than ordinary wine vinegar with coloring and added sugar. Legally, according to the rules of the Consortium, these are not allowed to be called "traditional".

Balsamic vinegar is very highly appreciated and valued by chefs and gourmet food lovers. Balsamic vinegar was almost unknown outside of Italy until the 1980s.