Probiotics refer to the living microorganisms, whose consumption is regarded to have health benefits, generally by restoring and improving gut flora. They are safe to consume but they may result in side effects and bacteria-host interactions in some situations. Probiotic-fortified foods, fermented dairy products and other fermented foods contain live probiotic cultures. Lactic acid bacteria (LABs), that are food fermenting bacteria, prevent food from spoilage and can increase the nutritional content of the foods they live in. There are several fermented products, which contains LAB, such as pao cai, kimchi, sauerkraut, pickled vegetables, etc. They are assumed to be beneficial in decreasing gastrointestinal discomfort, relieving constipation and evading the common cold. This book contains some path-breaking studies on probiotics. It strives to provide a fair idea about their applications in food and pharmacology. This book aims to serve as a resource guide for students and experts alike and contribute to the growth of research in this area of study.