Book excerpt: The book provides an overview on how the microbiome contributes to human health and disease. The microbiome has also become a burgeoning field of research in medicine, agriculture & environment. The readers will obtain profound knowledge on the connection between intestinal microbiota and immune defense systems, medicine, agriculture & environment. The book may address several researchers, clinicians and scholars working in biomedicine, microbiology and immunology. The application of new technologies has no doubt revolutionized the research initiatives providing new insights into the dynamics of these complex microbial communities and their role in medicine, agriculture & environment shall be more emphasized. Drawing on broad range concepts of disciplines and model systems, this book primarily provides a conceptual framework for understanding these human-microbe, animal-microbe & plant-microbe, interactions while shedding critical light on the scientific challenges that lie ahead. Furthermore this book explains why microbiome research demands a creative and interdisciplinary thinking—the capacity to combine microbiology with human, animal and plant physiology, ecological theory with immunology, and evolutionary perspectives with metabolic science.This book provides an accessible and authoritative guide to the fundamental principles of microbiome science, an exciting and fast-emerging new discipline that is reshaping many aspects of the life sciences. These microbial partners can also drive ecologically important traits, from thermal tolerance to diet in a typical immune system, and have contributed to animal and plant diversification over long evolutionary timescales. Also this book explains why microbiome research presents a more complete picture of the biology of humans and other animals, and how it can deliver novel therapies for human health and new strategies.