The stomach is located on the left side of the human body in the upper part of the abdominal cavity. It is a muscular organ and is part of the digestive tract. It communicates with the esophagus through the cardia and with the small intestine through the pyloric sphincter.
The stomach's role is to secrete enzymes called proteases, which break down proteins and acids, including hydrochloric acid, to facilitate digestion. It also performs muscle contractions in order to churn its contents and speed up digestion. The partially digested food is called chyme and exits the stomach through the pyloric sphincter to continue digestion in the small intestine.