It is written by keeping in mind the perspectives of both undergraduate (UG) and postgraduate (PG) students and in accordance with the Competency-Based Medical Education curriculum recommended by the National Medical Commission. Continuing the legacy of previous editions, this edition presented the complexity of the subject in a student friendly manner to make the revision of the course easier and quicker. Authors  include information pertaining to both theory and practical aspects. The unique chapter added for the first time in this edition is the Case Based Discussion, which will help students perform -better during practical examination. Scenarios for self-practice have also been included. An innovatively crafted and dedicated chapter on the Basics of Important Communicable Diseases has been added to make learning easier and practical aspects. This edition is also going to help all the faculty in their day-to-day teaching and in preparing for competitive examinations as well.