Human stomach acid is very strong, with a typical pH ranging from about 1 to 2, making it highly acidic. This level of acidity is close to that of battery acid and is necessary for breaking down food, killing harmful microbes, and activating digestive enzymes in the stomach. The main component of stomach acid is hydrochloric acid (HCl), which is produced by specialized cells in the stomach lining. Despite its strength, the stomach is protected by a thick mucus layer and bicarbonate to prevent damage to its own tissues.