The purpose of this study is: * to find out out the number of children who develop crohn's disease (CD) and ulcerative colitis (UC) each year and are living with the disease and to see how this differs by age groups. * to understand how children of different age groups are treated over time and how their treatment changes as they grow. * to assess how often children use healthcare services and how much this costs for different age groups over several years. CD and UC are long-term diseases that cause inflammation in intestine (part of digestive system) and develop ulcers.