The P=NP question is one of the great problems of science, which has intrigued computer scientists and mathematicians for decades. Despite the abundant research in theoretical computer science regarding the P=NP question, it has not been solved. The P=NP Question and Godel's Lost Letter covers historical developments (including the Godel's Lost letter), the importance of P=NP and the future of P=NP. This guide is also based on a new blog by the author, located at http: //rjlipton.wordpress.com. Jin-Yi Cai, an Associate Professor in computer science at the University of Wisconsin remarks 'I think it is the single most interesting web blog I have seen on related topics. He has a great insight and wit and beautiful way to see things and explain them.' Richard DeMillo, a professor in computer science at Georgia Tech remarks, 'This is a much needed treatment of great open problem computing.' The P=NP Question and Godel's Lost Letter is designed for advanced level students and researchers in computer science, and mathematics as a secondary text and reference book. Computer programmers, software developers and IT professionals working in the related industry of computer science theory, will also find this guide a valuable asset.