Part I: Current State of Knowledge regarding the Human Microbiome Structure, Function, and Diversity -- Chapter 1. Impact of Dietary Habits, Ethnicity and Geographical Provenance in Shaping Human Gut Microbiome -- Chapter 2. Methods Used for Studying Human Microbiome -- Chapter 3. Factors Affecting Composition of the Human Microbiome -- Part II: Correlation of the Human Microbiome to Specific Health/Disease Conditions -- Chapter 4. Mapping the Microbial Metabolites in Metabolic Disorders -- Chapter 5. Human Microbiome in Malnutrition -- Chapter 6. Human Microbiome and the Immune System Functioning -- Chapter 7. Human Microbiome and the Susceptibility to Infections -- Chapter 8. Human microbiome and the neurological disorders -- Chapter 9. Exploring the Unexplored Arena: Butyrate As a Dual Communicator in the Gut-Brain Axis -- Chapter 10. Human Microbiome and Lifestyle Disorders -- Chapter 11. Correlation of Human Microbiome and Immune Functioning to Covid-19 Infections:An Overview -- Chapter 12. Exploring the Pathoprofiles of SARS-COV-2-infected Human Gut-Lungs Microbiome Crosstalks -- Chapter 13. Role of Human Microbiome in Cardiovascular Disease: Therapeutic Potential and Challenges -- Chapter 14. The Human Microbiome and Respiratory Diseases -- Part-III: Manipulation of the Human Microbiome for Better Health -- Chapter 15. Probiotics: An Emerging Strategy for Oral Health Care -- Chapter 16. Dietary Modulation of Nervous and Immune System: Role of Prebiotics/ Synbiotics/ Postbiotics -- Chapter 17. Probiotics for Skin Health -- Chapter 18. Human Microbiome and Autism-Spectrum Disorders -- Chapter 19. Psychobiotics as an Emerging Category of Probiotic Products -- Chapter 20. Probiotics for Vaginal Health -- Chapter 21. Interactions between Microbial Therapeutics and the Endogenous Microbiome -- Part IV: Applied and Translational Aspects -- Chapter 22. The Role of a Multi-Spore Probiotic in the Management of Metabolic Endotoxemia - A Major Driver of Chronic Illness -- Chapter 23. Characterization and Authentication of Probiotic Preparations -- Chapter 24. A Survey of Commercially Available Probiotics and Prebiotics -- Chapter 25. Regulatory Aspects Relevant to Probiotic Products -- Chapter 26. Probiotic Identity from Spore - Focus on Bacillus Probiotics.