What is the difference between diverticulosis and Diverticulitis?

In middle age, about 50% of people experience thickening of the circular muscles in the sigmoid colon. These thick muscles become very strong and squeeze out knuckles of the colon lining tissue between gaps in the muscles, leading to the development of lining tissue sacs which project outward from the bowel wall. These sacs are called "diverticula," and the condition is known as diverticulosis. If these sacs become infected or inflamed, the inflamed or infected diverticula constitute "diverticulitis." If the diverticula rupture, intestinal contents leak into the abdominal cavity leading to peritonitis or abscess formation.