Gastroenterologists focus on the gastrointestinal (GI) tract, which includes the esophagus, stomach, intestines, colon, and rectum, as well as biliary organs such as the liver, pancreas, gallbladder, and bile ducts. They diagnose and manage conditions like irritable bowel syndrome (IBS), gastroesophageal reflux disease (GERD), peptic ulcers, hepatitis, pancreatitis, colon polyps, and inflammatory bowel disease (IBD). They also address nutritional issues and liver-related disorders.