Fermentation is a metabolic process where microorganisms like bacteria, yeasts, or fungi break down carbohydrates (such as sugars and starches) into other compounds like acids or alcohol in an oxygen-limited environment.

This process alters the flavor, aroma, and texture of foods while also often increasing their shelf life and nutritional value. Examples include yogurt, sauerkraut, kimchi, wine, beer, sourdough bread, and cheese.