The primary product of fermentation in yeast is ethanol (alcohol) and carbon dioxide. This anaerobic process occurs when yeast cells convert sugars into energy in the absence of oxygen, primarily for their metabolic needs. In addition to ethanol, fermentation also produces other byproducts, including organic acids and gases. The production of ethanol is utilized in various industries, including brewing, winemaking, and biofuel production. Understanding yeast fermentation is essential for both traditional craftsmanship and modern biotechnological applications.