Many people have small pouches in the lining of the colon, or large intestine, that bulge outward through weak spots. Each pouch is called a diverticulum. Multiple pouches are called diverticula. The condition of having diverticula is called diverticulosis. About 10 percent of Americans older than 40 have diverticulosis.

The condition becomes more common as people age. About half of all people older than 60 have diverticulosis.

Diverticula are most common in the lower portion of the large intestine, called the sigmoid colon...

FOR MORE DETAILS http://digestive.niddk.nih.gov/ddiseases/pubs/diverticulosis/