Lactic acid is a naturally occurring organic acid commonly found in sour milk products and various fruits. It is produced during anaerobic respiration in muscle cells and is responsible for muscle fatigue and soreness. Lactic acid is widely used in the food, pharmaceutical, and cosmetic industries as an acidulant, preservative, and flavoring agent. It is also utilized in the production of biodegradable polymers and as a precursor for the synthesis of other chemicals.