Red wine vinegar is vinegar made from essentially any variety of red wine. Many of the more expensive versions are made from specific types of wine, like merlot or pinot noir, though most of the vinegars available for sale are made from wine blends that might not be as appealing to drink. Vintners often set leftover and run-off wine aside for vinegar production as a way to make it useful, and people usually buy vinegar more for its general flavor than for the nuanced taste that wine is often famous for. In vinegar form, red wine is highly acetic, virtually calorie-free, and completely non-alcoholic. Cooks use it to add flavor and tang to salad dressings, sauces, and marinades, and it can also be used in pickling and preserving.