Carboxylic acids are more acidic than alcohols or phenols, although all of them have a hydrogen atom attached to an oxygen atom (—O—H) because the conjugate base of carboxylic acids or the carboxylate ion is stabilized by resonance. Due to the resonance in carboxylic acids, the negative charge is at the more electronegative atom (oxygen atom), whereas, in alcohols or phenols, the negative charge is on less electronegative atom. Thus, carboxylic acids can release proton easier than alcohols or phenols.