New diagnostic techniques, therapeutic modalities and preventive strategies make it mandatory that any book in the field of medicine be updated every few years. The resounding success of the last two editions of this book in 2010 and 2016, respectively, has encouraged us to bring out the third edition. The book has been extremely popular with undergraduates, postgraduates and teachers, who appreciate the unique features of the book and use it as a ready reckoner for learning and teaching.