Vinegar can be made from any fruit, but the most common ingredient is grapes. The fruit is fermented with the addition of a microorganism like yeast, which turns the sugars in the fruit into alcohol. To make vinegar, a second group of bacteria known as Acetobacter turn the alcohol into acetic acid, which is another name for vinegar.
Vinegar has a wide variety of uses, like as a ceramic cleaner, but is mainly used as a food seasoning and pickling liquid. Vinegar can be added to many foods to improve their taste, most commonly salad dressing and sauces. There are typically very few calories in high-quality vinegar.