Hiatal hernia is a condition where the stomach and other intra-abdominal contents protrude through the esophageal hiatus of the diaphragm. Risk factors include obesity, increased abdominal pressure, and previous hiatal hernia surgery. Symptoms may include heartburn, dysphagia, chest pain, or respiratory issues. Diagnosis is typically made through upper gastrointestinal imaging. Treatment depends on symptoms and hernia type but may involve lifestyle changes, medication, or surgery to repair the diaphragmatic defect and prevent acid reflux. Complications can include obstruction, bleeding, stomach twisting, and Barrett's esophagus.