Crohn's disease is one of two major types of inflammatory bowel diseases (IBD)--the general term for diseases that cause inflammation in the intestines--and has no cure and a high rate of recurrence following treatment. It usually occurs in the lowest portion of the small intestine (ileum), and the large intestine (colon or bowel), but it can occur in other parts of the digestive tract. Crohn's usually involves all layers of the intestinal wall. The disease can be difficult to diagnose because its symptoms, which include chronic diarrhea, crampy abdominal pain, loss of appetite, and weight loss, often mimic those of the other IBD type--ulcerative colitis--which affects only the colon.

An overview of types of Crohn's Disease
Crohn's Disease - Symptoms and Treatment