The Local Group of galaxies consists of the Milky Way and all of its neighbors. The proximity of these galaxies allows for detailed studies of the processes that have led to their formation, structures, and evolution. In particular, studies of the Local Group can test predictions of structure formation that are based on dark energy and cold dark matter. This book presents a collection of review papers, written by world experts, on some of the most important aspects of Local Group Astrophysics. It is an invaluable resource for both professional researchers and graduate students in this cutting-edge area of research.