Vinegar is a centuries old ingredient made from fermented liquids such as wine, beer and fruit juices which have had bacteria introduced that turns the liquid into acetic acid. Common varieties include distilled vinegar, wine vinegar, cider vinegar and Balsamic vinegar. There are countless other types too like date vinegar or champagne vinegar; each with its own special nuance. See individual types for substitutions and equivalents and see below for generic vinegar substitution recommendations.
Vinegar is used extensively in cooking for salad dressings, marinating and pickling foods, deglazing pan for pan sauces. Additionally white distilled vinegar is used for household cleaning chores including window cleaner and a great descaler for coffee pots.