Peritonitis is an inflammation of the peritoneum, the thin tissue lining the abdominal cavity and covering the abdominal organs. It can occur due to infection, injury, or underlying medical conditions, such as a ruptured appendix or perforated ulcer. Symptoms often include severe abdominal pain, fever, and a swollen abdomen. Treatment for peritonitis typically involves antibiotics to fight infection and may require surgery to address the underlying cause. If left untreated, it can lead to serious complications, including sepsis, which is a life-threatening response to infection. Early diagnosis and prompt medical care are crucial for recovery.