1/ Alcohol by volume
It is defined as the number of millilitres (mL) of pure ethanol present in 100 mL of solution at 20 °C (68 °F).
The number of millilitres of pure ethanol is the mass of the ethanol divided by its density at 20 °C, which is 0.78924 g/mL. The ABV standard is used worldwide. The International Organization of Legal Metrology has tables of density of water–ethanol mixtures at different concentrations and temperatures.
In some countries, such as the U.K and France, alcohol by volume is referred to as degrees Gay-Lussac (after the French chemist Joseph Louis Gay-Lussac), although there is a slight difference since Gay-Lussac used 15 °C (59 °F).
2/ 0% Alcohol by volume
Alcohol free, or non-alcoholic beverages, are non-alcoholic versions of typically alcoholic beverages.
0% ABV Malt Beer does not contain alcohol, hence it is not an alcoholic beverage.