The third edition of Microbiology in Nutshell has been written with the objective to include relevant information of new discoveries related to microbiology. Each chapter has been carefully updated and revised extensively. Beside these, a new chapter on 'Emerging and Reemerging Infections' has been added to update the knowledge. A new and innovative chapter 'Essentials of Microbiology at Glance' has been included to revise various aspects of all important microganisms in no time. Constructive suggestions from students and teachers were also taken into consideration while revising the book.