What does “proof” measure in alcoholic beverages?

"Proof" is a measurement that quantifies the alcohol content in an alcoholic beverage. Specifically, proof is defined as twice the alcohol by volume (ABV) percentage. For example, if a beverage has an ABV of 40%, it is said to be 80 proof. This measurement system originated in the early 18th century, and it serves as a standard that helps consumers understand the strength of the alcohol they are consuming.

Understanding proof is essential for evaluating the potential intoxicating effects of a drink, as higher proof corresponds to a higher concentration of alcohol. The other options, such as legal age of consumption, quality of ingredients, or total volume of liquid, relate to different aspects of alcohol policies and production but do not pertain to the breakdown of alcohol measurement or its effects in the same context. Thus, focusing on proof provides valuable insight into the potency of alcoholic beverages.