This book delves into the fundamental principles that underpin the classification and understanding of bacteria, from the basic concepts to the latest advances. This book encompasses numerous topics related to diversity, such as speciation and evolution of species, microbial diversity, and methods for estimating diversity and taxonomy of bacteria. The reader can gain valuable insights into the cutting-edge techniques used to identify and classify bacteria, such as genomics, metagenomics, and phylogenetic analysis. With expert contributions from leading scientists, this comprehensive guide offers a holistic view of the microbial world in the context of their role in global biodiversity, and explores the upcoming role of machine learning and artificial intelligence for exploration of bacterial diversity. For students and researchers in microbiology, genetics and biotechnology, this book is an essential resource for unravelling the mysteries of bacterial speciation, evolution, diversity, and taxonomy.