Viruses: A Very Short Introduction outlines the origins, structure, and method of infection of a vast variety of viruses and demonstrates how clever these entities appear to be. It explains the vital role viruses play in the ocean’s delicate ecosystem and discusses the impact of global warming, which is increasing the range of vector-transmitted viruses such as dengue, yellow fever, and West Nile virus. The recent Ebola and Zika epidemics, as well as Middle East Respiratory Syndrome, are also discussed. Can we ever live in harmony with viruses? This VSI considers the ways in which we may need to adapt to prevent emerging viruses with devastating consequences.