If you are a mathematician and want to know what QFT and string theory (ST) are about, or if you are a string theorist, but want to know more about the mathematics behind the theory, then this book is what you are looking for. This book is totally different than any other standard textbook on QFT or ST. Mathematicians will love the fact that it is written in a language that is (close to) theirs, and physicists will enjoy it (provided they have a more solid background in mathematics than the average practical physicists), because it shows QFT and ST from completely "new" angles. The book is a collection of lectures given by the various contributors, which fit together perfectly . The first volume has a very good overview of concepts and definitions at the very beginning and serves as a more mathematically oriented introductory treatment of SUSY and QFT with many advanced topics near the end. The second volume starts with an axiomatic approach of CFT and its use in string theory and then quantises strings with the BRST method (on a more mathematical level than usual), which is done superbly.It's a great reference, a wonderful textbook and a true delicacy in modern mathematical physics. A MUST HAVE for every mathematically inclined physicst or any mathematician with interests in physics! Great value for money...