The study of unicellular, multicellular and acellular microscopic organisms is known as microbiology. The various sub-fields studied under the umbrella of microbiology are bacteriology, virology, mycology, protistology and parasitology. Bacteriology is the branch of microbiology which deals with the study of the morphology, physiology, genetics and biochemistry of bacteria whereas the study of various aspects related to viruses is termed as virology. Microbiology can be classified into in diverse sectors such as food microbiology, medical microbiology, industrial microbiology and soil microbiology. It studies the pathogenic microorganisms which cause diseases in humans, as well as the useful microorganisms which are responsible for beneficial processes such as fermentation and antibiotic production. Some of them are also used as vectors for transferring foreign DNA into plants and animals. This book outlines the theories and applications of microbiology in detail. It provides significant information of this discipline to help develop a good understanding of microbiology and related fields. This book will serve as a valuable source of reference for graduate and post graduate students.