What does IBU stand for?

The correct definition of IBU is "International Bitterness Unit." This unit measures the bitterness of beer, which primarily comes from the hops used during brewing. The IBU scale quantifies the concentration of bitter compounds, particularly iso-alpha acids, in the beer. A higher IBU indicates a more bitter beer, while a lower IBU signifies less bitterness. Understanding IBU is crucial for beer enthusiasts and professionals alike, as it plays a significant role in flavor profiles and beer style classifications.

The other terms listed, although they may sound plausible, do not represent the standardized measurement used in brewing. "International Brewing Unit," "Internal Beer Unit," and "Inferred Bitterness Units" are not recognized terms within the brewing community or industry standards. Thus, the choice "International Bitterness Unit" is the most accurate and recognized definition for IBU.