Gastroenterology is the branch of medicine that focuses on the diagnosis and treatment of diseases of the digestive system. It includes the study of the esophagus, stomach, intestines, liver, gallbladder, and pancreas. Gastroenterologists specialize in the diagnosis and treatment of digestive disorders, including irritable bowel syndrome, inflammatory bowel disease, gastroesophageal reflux disease, and liver diseases. They also diagnose and treat conditions related to nutrition, food allergies, and celiac disease.