Term 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 group carboxylic acids are present in free, bound and to a small extent also in volatile form. The term "acid" is not to be understood negatively, because without this important component a wine tastes flat and flat. Only then does it gain refreshing power and the sweetness is also shown to its best advantage. Wines from hot regions often have a lower content. Unripe grapes have a high proportion of each grape variety.