This edition also features incorporation of parasitology, which has been deftly included to add value to the book. Unnecessary details of various parasites have been excluded. This obviates the reading of a separate book on parasitology. The text is presented in a simple and lucid manner. It is fully illustrated with colour and computer-drawn diagrams, clinical photographs and photomicrographs. These make the book attractively colourful and the readers can have a far better understanding of the biology of microorganisms. New illustrations have been added at various places for in-depth comprehension of the topics. For quick review and recapitulation, key facts and multiple choice questions have been added at the end of each chapter. To help the students perform better in the examination, the competencies expected from the students after reading various chapters have been outlined in the beginning of the chapters.