Grain alcohol is a purified form of ethyl alcohol (ethanol) made from the distillation of fermented grain. The ethanol is produced via fermentation of sugars in the grain by yeast prior to repeated distillation or rectification. The term "grain alcohol" may be used to refer to any ethanol produced from grain or another agricultural origin (as in beer or vodka) or it may be reserved to describe alcohol that is at least 90% pure (e.g., Everclear).

What damage does alcohol do to our bodies?

From a chemistry perspective, there are several types of alcohol, but the one of interest here is the alcohol you can drink, which is ethyl alcohol or ethanol. Technically, none of the types of alcohol go bad or expire in pure form or when diluted with water. Alcohol is a potent disinfectant, so when it is present in a high enough concentration, it's safe from mold, fungi, protozoa, and bacteria. It's only when alcohol is mixed with other ingredients that it has a shelf life.