While the traditional role of epidemiology was the study of communicable diseases, it has evolved to a modern approach geared towards the study of the increasing incidence of non-communicable chronic diseases. Epidemiology may be defined as the collection of large sample sizes and the measurement of numerous variables from stored samples to facilitate estimation of disease risk over time, and may involve the development and use of new techniques to acquire dependent and independent variables . Nevertheless, the traditional view of epidemiology remains embedded as the study of epidemics. In studying Inflammatory Bowel Disease (IBD) as an epidemic, several aspects were addressed at ECCO'19 Copenhagen Congress, including changes in the incidence/prevalence of IBD in different populations (countries), effects of therapy on surgical rates, the incidence of complications such as colorectal cancer, the impact of treatment patterns and findings in smaller sub-populations such as patients with elderly-onset and perianal Crohn’s Disease (CD). Although the modern definition carries a risk that studies will be conducted without a specific hypothesis thereby generating statistically significant observations of no clinical relevance nor benefit, the studies presented at ECCO 2019 addressed clinically important questions.