This book provides insight into major facets of the physics of quantum gravity. The application of quantum field theory for explaining gravity is one of the main problems in contemporary elementary Physics. It has been in existence for nearly a century, but a definite answer is yet to be determined. Loop quantum gravity and string theory have answered several answers associated with this problem, but they have brought with themselves a huge set of added questions. Apart from these two theories, several other alternative theories have also been developed over the decades. Renowned authors from across the globe have contributed in this book. The content provided in this book deals with gravity and its quantization through known and alternative methods in order to provide a better understanding on the quantum nature of gravity. Readers will find an extensive compilation of physical and mathematical concepts along with updated research regarding the challenging puzzle of quantum gravity in this book.