Phenols are a class of organic compounds that contain a hydroxyl group (-OH) attached to an aromatic hydrocarbon group, typically a benzene ring. They are characterized by their ability to act as weak acids, as the hydrogen of the hydroxyl group can dissociate, forming phenoxide ions (C₆H₅O⁻). Phenols are widely used in the chemical industry for the synthesis of plastics, resins, and antiseptics, and they are key intermediates in the production of drugs, dyes, and fragrances.