Viruses are everywhere, and as the COVID-19 pandemic has shown, cannot be ignored. From their discovery to the unravelling of their intricate structures, this Very Short Introduction provides a rounded and concise account of the nature of viruses, how they attack their hosts, and the efforts to control them. In this new edition, Dorothy Crawford examines the recent rise in emerging virus infections, especially coronaviruses, including the viruses behind SARS and MERS, and SARS CoV-2 responsible for COVID-19. Crawford explores why the SARS-CoV-2 was able to spread rapidly to form a pandemic while others have produced more localized epidemics, as well as looking at the revolution in vaccine production that this has caused. Looking to the future, this Very Short Introduction considers the preventative measures and management of future dangerous viruses that are expected to emerge.