A hiatal hernia occurs when a part of the stomach pushes through the diaphragm into the chest cavity. The diaphragm is a muscle that separates the chest from the abdomen and helps with breathing. This condition can lead to symptoms like heartburn, chest pain, and difficulty swallowing. There are two main types of hiatal hernias: sliding and paraesophageal. A sliding hiatal hernia is the most common type, where the stomach and the section of the esophagus that joins the stomach slide up and down. In contrast, a paraesophageal hiatal hernia occurs when part of the stomach pushes through the diaphragm and sits next to the esophagus, which can lead to more serious complications.