This is quite simply the best book on the Ricci Flow that I have ever encountered. This is the only book on the Ricci Flow that I have ever encountered. I believe that its value to the development and application of geometric analysis for the study of manifolds is incalculable (no pun intended). I must say, I have never seen nicer functions or such improved metrics. I am particularly impressed by by the talents of the second author, Dr. Dan Knopf, as displayed in this fine publication. His commanding grasp of the material, lucid and thought-provoking presentation, and fine expository style are nothing short of breathtaking. I am pleased to recommend this excellent work.