Résumé : The mathematical models used to produce a simplified description of reality appear as important modern epidemiology tools. Indeed, a goal in epidemiology is to understand how pathogens are transmitted between individuals. This would predict epidemics and their extent in time and space. The models can provide a guide to public health practitioners, through comparison of different strategies in disease management. Also, it improves our understanding of pathogen transmission. Here, we focused on some of these models to emphasize their practical value in understanding the influenza viruses’ circulation. First, we present a simple epidemiological model that provides an understandable approach to follow in order to build a model. Second, we show how to use such simple models to include the epidemic process in a more global scale. Finally, we explain how modeling can help investigate the extent to which a pathogen can trigger an epidemic or the effects of public health measures on evolving influenza viruses.