Whether wine, beer or spirits are more your jam, these boozy beverages have one thing in common: All of them contain alcohol, which means that they all have undergone the process of fermentation. Fermentation is a pretty commonly used term in the alcohol industry, and although the overarching concept is relatively simple to grasp, many imbibers aren’t fully aware of the intricacies of this essential booze-creating process.
Alcoholic fermentation, also referred to as ethanol fermentation, is a biological process by which sugar is converted into alcohol and carbon dioxide. Yeasts are responsible for this process, and oxygen is not necessary, which means that alcoholic fermentation is an anaerobic process. Byproducts of the fermentation process include heat, carbon dioxide, water and alcohol. In this case, we’re focusing on the latter.
Humans have been using the process of ethanol fermentation for millennia. The ancient Greeks were known for their mead production, which was produced by fermenting honey and water. In the meantime, though, honey has taken a back seat to other foodstuffs, most commonly grains (for beer and spirits) and grapes (for wine). Additional base products include other fruits, such as berries, apples and so on, rice (for sake) and beyond.
https://www.nature.com/scitable/topicpage/yeast-fermentation-and-the-making-of-beer-14372813/