This textbook teaches the basic principles of prokaryotic physiology, biochemistry, and cell behavior in a concise, detailed fashion. It covers a broad range of topics of general interest including, intermediary metabolism, macromolecular synthesis, cell growth and division, and responses to changes in external growth conditions. Metabolic and behavioral activities of different bacteria and archaea are described and compared with each other. In order to aid students in researching the subject material, the text is extensively referenced and end notes are supplied that provide additional information, including the experimental bases for some of the major conclusions. Each chapter concludes with a summary emphasizing the major points covered, and a set of study questions to help the students to learn the material. The text is organized according to topics rather than organisms which lends itself to elucidation of general principles of physiology and metabolism, even through the physiology of specific groups of prokaryotes is emphasized.