Diverticular disease is the general name for a common condition that causes small bulges (diverticula) or sacs to form in the wall of the large intestine (colon). Although these sacs can form anywhere in the colon, they are most common in the sigmoid colon (part of the large intestine closest to the rectum).

Diverticulosis: The presence of diverticula without associated complications or problems. The condition can lead to more serious issues including diverticulitis, perforation (the formation of holes), stricture (a narrowing of the colon that does not easily let stool pass), fistulas, and bleeding.
    
Diverticulitis: An inflammatory condition of the colon thought to be caused by perforation of one of the sacs. Several secondary complications can result from a diverticulitis attack. When this occurs, it is called complicated diverticulitis.