Inflammatory bowel disease has become one of the most rapidly changing fields within gastroenterology. This is especially important as Crohn's disease, in particular, appears to be entering a new phase of increasing incidence and prevalence. Clinical practice is, fortunately, poised to take advantage of the new opportunities for immunological manipulation. This work aims to present current knowledge in a compact and digestible format designed to enable doctors to take full advantage of that knowledge in such a way as to meet their own needs most appropriately. Topics include aetiology, epidemiology, pathology, clinical presentation, acute severe colitis and imaging/endoscopy.