The primary ingredient used in the fermentation process is typically sugar, which serves as an energy source for microorganisms such as yeast or bacteria. During fermentation, these organisms metabolize the sugar anaerobically, resulting in byproducts like ethanol and carbon dioxide. This process is crucial in producing various food and beverage items, including bread, beer, and yogurt. The effectiveness of fermentation depends on several factors such as temperature and pH, which influence the growth and activity of the fermenting agents.