Every animal, whether human, squid, or wasp, is home to millions of bacteria and other microbes. Many people think of microbes as germs to be eradicated, but those that live with us—the microbiome—build our bodies, protect our health, shape our identities, and grant us incredible abilities. In this astonishing book, Ed Yong takes us on a grand tour through our microbial partners, and introduces us to the scientists on the front lines of discovery. Yong, whose humor is as evident as his erudition, prompts us to look at ourselves and our animal companions in a new light—less as individuals and more as the interconnected, interdependent multitudes we assuredly are. The microbes in our bodies are part of our immune systems and protect us from disease. Those in cows and termites digest the plants they eat. In the deep oceans, mysterious creatures without mouths or guts depend on microbes for all their energy. Bacteria provide squids with invisibility cloaks, help beetles to bring down forests, and allow worms to cause diseases that afflict millions of people. I Contain Multitudes is the story of these extraordinary partnerships, between the creatures we are familiar with and those we are not. It reveals how we humans are disrupting these partnerships and how we might manipulate them for our own good. It will change both our view of nature and our sense of where we belong in it.