Viruses are keyplayers in both the earth ecosystems and in the human society. New viraldiseases are emerging continuously. Viruses adapt to new environments atastounding rates. Genetic variability of viruses jeopardizes vaccine efficacy.For many virus mutants resistant to antiviral agents or host immune responsesarise readily, for example, with HIV and influenza. These variations are all ofutmost importance for human and animal health as they have prevented us fromcontrolling these epidemic pathogens. This course focuses on the mechanisms that viruses use to evolve,survive and cause disease in their hosts. Covering human, animal, plant and microbial viruses, it provides boththe basic foundations for the evolutionary dynamics of viruses and specificexamples of emerging diseases.