The alcoholic potency of beverages is, except for wine and beer, expressed as "Proof". Proof is the alcoholic content (by volume) multiplied by 2. Most distilled spirits are 80 proof, or 40% alcohol. Some rums go as high as 151 proof (75.5% alcohol) and bourbons can be 101 proof (50.5% alcohol).
Wines range around 12% alcohol, and beers are usually in the range of 3.2% to 6%.