Alcohol by volume (abbreviated as abv or ABV) is a standard measure of how much alcohol (ethanol) is contained in an alcoholic beverage (expressed as a percentage of total volume). The abv standard is used worldwide. In some countries, alcohol by volume is referred to as degrees Gay-Lussac (after the French chemist Joseph Louis Gay-Lussac).
Another way of specifying the amount of alcohol is alcoholic proof, which is twice the alcohol-by-volume number.