As an engineer and faithful follower of theoretical physics, I was trying to understand Superstring Theory. After "The universe elegant" (Greene) and "The Cosmic Landscape: String Theory and the Illusion of Intelligent Design" (Suskind), and even "The Trouble With Physics: The Rise of String Theory, the Fall of a Science, and What Comes Next" (Smolin),  I have been fortunate to encounter this book. Barton Zwiebach offered a pedagogic and intelligent exposition. Everything is explained with so good figures, Lagrangian and Action Principle as main rules for deductions, evolution scheme from just a point to D-branes, explanation of every assertion and formulae, updating with current state of the art, orientations for further readings, all of them are just some of the virtues of this book. Its lectures allow me to get more lectures about the subject. Thanks to Mr Zwiebach for allowing me the opportunity to enjoy this book.