Corn Sugar, or dextrose, is used to "prime" your beer to produce natural carbonation in the bottle. "Priming" is the act of adding a small amount of fresh fermentable sugar to the beer just before bottling so that the residual yeast will consume it and produce carbonation in the sealed bottle. We recommend corn sugar for this purpose because it is easy for the yeast to consume and has a neutral flavor profile, meaning it will leave your beer tasting the way you designed it!