We can't see them, but microbes are the dominant form of life on Earth. They make up half of the world's biomass. They were here billions of years before we were, and they will be here after we are gone. Without their activity, life as we know it would be impossible. Even within our own bodies, there are ten times as many bacterial cells as human cells. Understanding Microbes provides a clear, accessible introduction to this world of microbes. As...