خميرة (Fermentation) is a natural process where microorganisms, such as yeast and bacteria, convert sugars into alcohol, gases, or acids. This process is essential in producing various foods and beverages, including bread, beer, and yogurt. During fermentation, these microorganisms break down carbohydrates, resulting in changes in flavor, texture, and nutritional content. Fermentation occurs in anaerobic conditions, meaning it can happen without oxygen. The process has been used for thousands of years in different cultures to preserve food and enhance its taste. Understanding fermentation helps in appreciating the science behind many traditional and modern culinary practices.