Crohn's disease and ulcerative colitis are the two main forms of inflammatory bowel disease. Crohn's can affect any part of the gastrointestinal tract and is characterized by transmural inflammation and granulomas. Ulcerative colitis only affects the colon and causes superficial ulcers. Both conditions are diagnosed based on symptoms, endoscopic findings, and histology. Treatment involves medications to induce and maintain remission as well as surgery for complications.