The purpose of this study is to evaluate the clinical effectiveness (how well the treatment works) of Guselkumab, by lines of treatment and subpopulations, and what are the outcomes of treatment (clinical outcomes) in adult participants with moderately to severely active Ulcerative Colitis (UC) or Crohn's Disease (CD) under real-world settings. CD and UC are the main type of Inflammatory bowel disease, a group of inflammatory conditions of the colon and small intestine.