The science of fermentation is wonderfully simple. Yeast eat sugar. They leave behind two waste products, ethyl alcohol and carbon dioxide. If we were being honest, we would admit that what a liquor store sells is, chemically speaking, little more than the litter boxes of millions of domesticated yeast organisms, wrapped up in pretty bottles with fancy price tags.
— The Drunken Botanist: The Plants that Create the World's Great Drinks: 10th Anniversary Edition by Amy Stewart