The International Bitterness Units or IBU is one way to measure how a beer tastes in terms of bitterness. While the bitterness of beer plays a significant role in a flavor profile, it is only one of many factors. Alcohol content, malt and water quality, yeast fermentation byproducts, bacteria, and aeration also affect a particular beer's taste profile.
Commercial brewers and homebrewers alike employ experimental and traditional brewing techniques to get their craft beer just right. One of those techniques is Krausening, a traditional German approach that eschews adding any sugars or extras to the fermented beer, with the goal of producing a "cleaner" beer. In summary, and ultimate effect, to kräusen a beer is to add carbonation to it.
The craft beer variety pack is the world's biggest gamble. You could get introduced to your next favorite IPA. Or, you could get stuck with Old Fezziwig.
