The book highlights the importance of prebiotics, probiotics and synbiotics in the signalling mechanism between gut microbiota and brain, also referred to as the gut-brain axis. A stable gut microbiota is essential for normal gut physiology and overall health, since it assists in proper signalling along the brain–gut axis. The book describes how the cross talks between gut microbiota and brain, not only regulate gastro-intestinal functions but also ensure proper functioning of cognitive behaviour and immunological functions. The various chapters describe probiotic microorganisms that colonize gastrointestinal tract and provide an array of health benefits to the host. It further elaborates about certain non-digestible oligosaccharides (prebiotics) are easily fermented by specialist microbes in the gut, to produce health-promoting metabolites and inhibit the growth of pathogenic bacteria.  This book is useful for students, researchers and scientists in the field of microbiology, food science and nutrition. It is also meant for industry experts involved in developing nutraceuticals.