Hydrochloric acid, or HCl, is a strong acid commonly found in laboratories and industries. It is a clear, colorless liquid with a sharp, pungent smell. HCl is highly corrosive and can react with many substances, making it useful for cleaning metals and adjusting pH levels in various processes. In the human body, HCl plays a crucial role in digestion. It is produced in the stomach to help break down food and kill harmful bacteria. This natural acid is essential for proper nutrient absorption and maintaining a healthy digestive system.