Acetic acid, also known as methylcarboxylic acid or ethanoic acid is a carboxylic acid with the chemical formula CH₃COOH. It is a colorless and volatile liquid with a characteristic strong and pungent odor (similar to vinegar). It is the main component of vinegar, which typically contains 4% to 8% acetic acid by volume.

One of the most common organic solvents, it reacts readily with other chemicals such as alcohols, bases, amines, amides and esters.