The human stomach is a hollow, muscular organ located in the upper abdomen, responsible for digesting food. It has four main regions: the cardia (where food enters), the fundus (the upper part), the body (the central area), and the pylorus (where food exits into the small intestine). The stomach secretes gastric juices containing hydrochloric acid and enzymes like pepsin, which break down food, especially proteins. Its muscular walls churn food to mix it with digestive enzymes, turning it into a semi-liquid substance called chyme. The stomach also acts as a storage reservoir, gradually releasing food into the small intestine for further digestion and nutrient absorption. The stomach is lined with a thick mucus layer to protect it from the harsh acidic environment.