From the reviews: <p> The aim of this book is to present the very active theory of Borcherds-Kac-Moody Lie algebras and of G-graded vertex algebras at a level accessible to graduate students and mathematicians from other fields. An introduction of this type is certainly very desirable a ] . The author of this review, being a mathematician from a different field a ] may be a good test person for this book. I like the concept of the book a ] . (Rainer Schulze-Pillot, Mathematical Reviews, Issue 2008 e)