A sour liquid produced by acetic fermentation of alcoholic liquids — wine, cider, malt, or distilled alcohol oxidized by acetic acid bacteria (Acetobacter, Gluconobacter). Vinegar contains typically 4–8% acetic acid, giving its sharp taste and preservative power: acidity below pH 4.6 inhibits most pathogens and spoilage organisms, which is why vinegar pickles and preserves foods. Traditional Orleans and submerged acetator processes differ in speed and flavour complexity; barrel ageing adds depth. Quality standards define minimum acidity, and authenticity testing distinguishes brewed vinegar from diluted synthetic acetic acid — a long-standing fraud issue.