Genetic investigations and manipulations of bacteria and bacteriophage have made vital contributions to our basic understanding of living cells and to the development of molecular biology and biotechnology. This volume is a survey of the genetics of bacteria and their viruses, and it provides students with a comprehensive introduction to this rapidly changing subject. The book is written for upper level undergraduates and beginning graduate students, particularly those who have had an introductory genetics course. The fifth edition has been extensively revised to reflect recent advances in the field. The book now has a reader-friendly look, with end-of-chapter questions, "Thinking Ahead" and "Applications" boxes to challenge students' comprehension and insights. A complete glossary of commonly used terms has been revised and expanded.