Acetic acid is a weak acid, and the defining ingredient in vinegar. Aside from its common use in food, acetic acid is an important industrial chemical.
Since prehistoric times, humans have produced acetic acid by exposing alcoholic beverages to aerobic bacteria usually of the acetobacter genus. The bacteria convert the alcohol to acetic acid. Distillation of the vinegar concentrates the acid.
There are several techniques used to produce acetic acid on an industrial scale.
Methanol and carbon monoxide are combined under pressure, in the presence of a catalyst.
Ethylene is oxidation in the presence of a palladium based catalyst.
Though acetic acid is commonly generated by certain microbes, in high enough concentrations it preserves food.
Acetic acid is used in the production of adheisives, inks, and asprin.