Kermesic acid, a natural dye originating from the insect species Kermes ilices, is structurally a 3,5,6,8-tetrahydroxy-9,10-anthraquinone with methyl and carboxy groups substituted at positions 1 and 2 respectively. This compound functions both as an animal metabolite and a dye. Classified chemically, it falls under the categories of tetrahydroxyanthraquinone and monocarboxylic acid. Additionally, it exists in the form of a conjugate acid of a kermesate.