We live in a world full of invisible enemies and normally we don’t even realize they’re there. But from time to time one of these microscopic creatures becomes powerful enough to turn everything upside down. We are witnessing now the rise of the coronaviruses, which are causing the worst global health crisis in decades, and we are wondering why we didn’t see this coming. But we did. Experts have been warning us for years about microbes, one of the most terrifying challenges we face as a species. Especially because nowadays, an outbreak of an infectious disease that starts in one corner of the planet can quickly become global thanks to our modern lifestyle. There have been many pandemics over the history of humanity, and Covid-19 is unlikely to be the last. What can we do to prepare ourselves better? The first thing is to understand what we are dealing with. Salvador Macip is a specialist in the biology of infectious diseases and here he explains, in a language everyone can understand, what it means to share the planet with millions of microbes, some wonderful allies, others terrible foes. He provides a concise account of the epidemics that changed history and then focuses on the great modern plagues that are still causing millions of deaths every year, including influenza, TB, AIDS and malaria. The coronaviruses, including the SARS-CoV-2 virus that causes Covid-19, are situated in the context of the many microorganisms that cause infectious diseases and epidemics. Macip also examines the methods we have used – from vaccines and drugs to improved sanitation and other practices like social distancing – to try to control these invisible enemies. This authoritative overview of modern epidemics and the pathogens that cause them will be essential reading for everyone who wants to understand the world in which we live today, a world in which some of the greatest threats to the human species come from the invisible microbes with which we share this planet.