When there is an accomplishment such as this book, do not presume that those listed as editors are the soul of the book. The authors are at the heart of each individual chapter. They take the seed of an idea and make it their own. The short amount of time, and amount of work required is not sufficiently awarded with thanks. To each of the authors and contributors to this book, you have our abiding gratitude. To those who contributed to the previous editions but could not participate in this book, your work laid the foundation for a much improved volume. Last but not least we would be remiss not to thank the people who helped shape ideas into an actual text. Laura Libretti had to collect, and e-mail, and collect information again and again from the authors; thanks for your part in making sure that every author and contributor receives recognition. Thanks to Kim Davis at McGraw-Hill Education (our project development editor yet again) because she is so easy to work with, and makes doing a text book fun. Without Kim the book would not be the excellent product that you are reading. The e-book is available because of Kim's extra efforts on our behalf. To other staff at McGraw-Hill Education who worked on the book but don't always get acknowledged, thanks; you know who you are. The last thanks, but not least at all, is for Michael Weitz who champions this book at every opportunity. We will always be grateful for your patience and understanding through a very trying year. This is our best book yet thanks to you. Our heartfelt thanks.