Inflammatory bowel disease (IBD) is the general term for diseases that cause inflammation in the intestines. Crohn’s disease and ulcerative colitis belong to the group of illnesses known as IBDs. Crohn’s disease may affect any part of the digestive tract, but it most often affects the ileum. Ulcerative colitis occurs only in the inner lining of the colon (the large intestine) and the rectum. Abdominal pain and diarrhea are the most common symptoms of both ulcerative colitis and Crohn’s disease. Both diseases are chronic, ongoing diseases, although periods of remission of not uncommon.