Acetic acid /əˈsiːtɨk/ (systematically named ethanoic acid /ˌɛθəˈnoʊɨk/) is anorganic compound with the chemical formula CH3COOH (also written as CH3CO2H or C2H4O2). It is a colourless liquid that when undiluted is also called glacial acetic acid. Vinegar is roughly 3 %-9 % acetic acid by volume,making acetic acid the main component of vinegar apart from water.Acetic acidhas a distinctive sour taste and pungent smell. Besides its production as household vinegar,it is mainly produced as a precursor to polyvinylacetate and cellulose acetate.Acetic acid is the second simplest carboxylic acid (the simplest is formic acid) and is an important chemical reagent and industrial chemical,mainly used in the production of cellulose acetate for photographic film and polyvinyl acetate for wood glue, as well as synthetic fibers and fabrics. In households, diluted acetic acid is often used in descaling agents. In the food industry, acetic acid is used under the food additive codeE260 as an acidity regulator and as a condiment.