The metabolic process that produces chemical changes in organic substrates by the action of enzymes is referred to as fermentation. It plays an important role in food production where it includes microorganisms for bringing desirable changes to a foodstuff or beverage. Fermentation is the primary means of producing ATP within microorganisms through the degradation of organic nutrients anaerobically. Some of the major products, which are produced using the process of fermentation are ethanol lactic acid and hydrogen gas. The procedures used within industrial fermentation are classified into batch and batch-fed procedures. The different ingredients are combined and the reactions proceed without any interference in the batch procedure. During the fed-batch procedure, a few ingredients are added during the process of fermentation. This book presents the complex subject of fermentation in the most comprehensible and easy to understand language. Different approaches, evaluations and methodologies on fermentation have been included herein. Experts and students actively engaged in this field will find this book full of crucial and unexplored concepts.