Methods in microbial systematics have developed and changed significantly in the last 40 years. This has resulted in considerable change in both the defining microbial species and the methods required to make reliable identifications. Developments in information technology have enabled ready access to vast amounts of new and historic data online. Establishing both the relevance, and the most appropriate use, of this data is now a major consideration when undertaking identifications and systematic research. This book provides some insights into how current methods and resources are being used in microbial systematics, together with some thoughts and suggestions as to how both methodologies and concepts may develop in the future. It includes coverage of: The philosophy and changes in microbial systematics, including the relevance of names, new concepts of species, and the issues encountered with species that cannot be grown in culture. The application of new identification technologies, specifically those based on nucleic acids and complex chemo-taxonomic methods. The challenges of using published databases and other data resources in arriving at an identification appropriate to current species concepts. The practical requirements of an identification: obtaining and verifying reference cultures and data, and the type and level of identification required by different users. This book is suitable for academic researchers, scientists involved with identification or survey, microbiologists, students and extension workers.