A human being is a symbiotic system that consists of a mammalian component interacting with a multiplicity of microbes, collectively referred to as the microbiota. The microbiota associated with humans is comprised of a variety of communities, the composition of each being dependant on the particular body site it inhabits. This book describes the various communities inhabiting humans as well as their important roles in human health and disease. An ecological approach has been adopted throughout the book to explain why the microbial community at a particular body site has a particular composition when in balance with the host (eubiosis), and why certain factors can disrupt the balance and induce dysbiosis. The techniques used to determine microbial community composition are discussed and a chapter is devoted to the many factors that underlie this mammalian-microbe symbiosis. The Human Microbiome In Health And Disease is aimed at senior undergraduates and graduates whose courses include a module on the indigenous microbiota of humans. It will also be useful to professional scientists, clinicians, and others who are keen to know more about the human microbiota and its role in health and disease.