A warning to compiler practitioners: This book is heavily based on mathematics. Ideas are expressed more often as algebra and theorems than as English prose. Therefore it's more of a resource for academic work than for actually implementing a compiler. If you are looking for such a formal treatment, perhaps as the basis of a thesis, I highly recommend this book. It's similar to the Dragon Book, but is more up to date and covers topics specific to imperative, functional, logic, and OO languages. But if you're simply interested in getting a working understanding of how to implement a compiler, I suggest one of the other highly rated works on Amazon. I think the other reviewer (only 2 reviews says something too) summarized it best: authoritative, informative, and dull.