Inflammatory bowel disease (IBD) is a classification for diseases which involve chronic inflammation in tissue of the digestive system. Crohn’s disease and ulcerative colitis are both inflammatory bowel diseases.
Irritable bowel syndrome (IBS) is not considered an inflammatory bowel disease because it does not involve any visible sign of inflammation.
For In-Depth Coverage of Crohn's Disease, see Amber J. Tresca's Site:
Related Reading from Dr. Bolen, Your IBS Guide:

