Designation for liquid or solid chemical compounds containing hydrogen. The hydrogen ions cause the acidic taste of a solution. A distinction is made between inorganic and organic acids. In wine, mostly organic acids of the carboxylic acid group are present in free, bound and, to a lesser extent, volatile form. The term "acid" is not to be understood negatively, because without this important component a wine tastes flat and insipid. Only then does it acquire refreshing strength and the sweetness comes into its own more effectively. Wines from hot regions often have a lower content. Unripe grapes have a high content, depending on the grape variety.