A hernia is a protrusion of an organ, or part of an organ, through its enclosing wall of through connective tissue. Common types of hernias are protrusion of an intestinal loop through the umbilicus (umbilical hernia) or inguinal canal of the groin (inguinal hernia), or protrusion of part of the stomach or esophagus into the chest cavity through the opening (hiatus) of the esophagus into the diaphragm (hiatus hernia).