Barton Zwiebach is once again faithful to his goal of making string theory accessible to undergraduates. Complete and thorough in its coverage, the author presents the main concepts of string theory in a concrete and physical way in order to develop intuition before formalism, often through simplified and illustrative examples. This new edition now includes AdS/CFT correspondence, which is the hottest area of string theory right now as well as introducing superstrings. The text is perfectly suited to introductory courses in string theory for students with a background in mathematics and physics. New sections cover strings on orbifolds, cosmic strings, moduli stabilization, and the string theory landscape.