Encyclopedia of Microbiology, Fourth Edition gathers both basic and applied dimensions in this dynamic field that includes virtually all environments on Earth. This range attracts a growing number of cross-disciplinary studies, which the encyclopedia makes available to readers from diverse educational backgrounds. The new edition builds on the solid foundation established in earlier versions, adding new material that reflects recent advances in the field. New focus areas include `Animal and Plant Microbiomes' and 'Global Impact of Microbes`. The thematic organization of the work allows users to focus on specific areas, e.g., for didactical purposes, while also browsing for topics in different areas.