A note about IBUs, that is, International Bitterness Units, also referred to as EBUs or European Bitterness Units.
IBU/EBU are a scale of bitterness, from 0 to 100, not considered to be an exact measure but good enough to provide assistance in the development of beer recipes and to aid the consumer in choosing between the beers on offer.
As a guide;
Less than 20 IBU: Low bitterness (Wheat beer)
20 -30 IBU: Moderate bitterness (Typical English Bitter)
30 – 45 IBU: High bitterness (Contemporary IPA)
More than 45 IBU: Very high bitterness (Imperial Stout)