A hiatal hernia (say "hi-AY-tul HER-nee-uh") is different from other types of hernias, because it involves the stomach instead of the intestine. It occurs when part of your stomach bulges up through your diaphragm and into your chest. The diaphragm is a sheet of muscle that separates your belly from your chest. You can't feel a hiatal hernia or see a bulge.
Most people with a hiatal hernia have no symptoms. But one symptom you may have is heartburn. If you often have symptoms, or if they are very bad, you may also have gastroesophageal reflux disease (GERD). A hiatal hernia can lead to GERD. It's common to have both problems at the same time.