A microbiota is an "ecological community of commensal, symbiotic and pathogenic microorganisms" found in and on all multicellular organisms studied to date from plants to animals. A microbiota includes bacteria, archaea, protists, fungi and viruses. Microbiota have been found to be crucial for immunologic, hormonal and metabolic homeostasis of their host. The synonymous term microbiome describes either the collective genomes of the microorganisms that reside in an environmental niche or the microorganisms themselves.

In the present book, fifteen typical literatures about Microbiome published on international authoritative journals were selected to introduce the worldwide newest progress, which contains reviews or original researches on Pretreatment gut microbiome, Human Microbiome Project, hospital microbiome, etc. We hope this book can demonstrate advances in Microbiome as well as give references to the researchers, students and other related people.