Final answer:
Hernias occur when peritoneal contents protrude through a defect in the abdominal wall, not to be confused with peritonitis, an inflammation of the peritoneum.
Step-by-step explanation:
Hernias are when the peritoneal sac and potentially peritoneal contents protrude through a weakness or defect in the muscle or fascia of the abdominal wall. The peritoneum is a broad serous membranous sac that holds digestive organs within the abdominal cavity in place. It is composed of two main regions: the parietal peritoneum which lines the abdominal wall, and the visceral peritoneum which envelopes the abdominal organs. This condition should not be confused with peritonitis, which is an inflammation of the peritoneum often resulting from infections or perforations in the digestive tract leading to potentially life-threatening complications.