We still do not know the causes of either main form of colitis, but we are getting closer. We do know, however, a lot about the changes that occur in the bowel of people with colitis, and how to return them to normal. It should be only a matter of time before we know why these changes happen, as well as what has happened. Colitis simply means 'inflammation of the large bowel' (the colon). Doctors use the word in only two contexts, ulcerative colitis and Crohn's disease, known collectively to doctors as 'inflammatory bowel disease'. People may also link irritable bowel syndrome and diverticular disease to colitis. It is often difficult to persuade people with irritable bowel syndrome that this is what they have, that it is not a true 'colitis' and they do not have something more serious, such as inflammatory bowel disease or cancer. Most of this book is devoted to ulcerative colitis and Crohn's, it would not be complete without chapters on how to distinguish these inflammatory bowel diseases from irritable bowel, diverticular disease and colon cancer, the symptoms of which can mimic those of colitis.