Indigestion, also known as dyspepsia, can be caused by underlying conditions like GERD, peptic ulcers, or issues with the pancreas or bile ducts. It can also occur without a known cause. Common symptoms include feeling full, epigastric pain, nausea, vomiting, heartburn, and belching. Diagnosis may involve physical exams, tests like x-rays or endoscopy, and ruling out other conditions. Making dietary changes like eating smaller meals, chewing food well, and reducing stress can help relieve indigestion symptoms at home.