As I complete the sixth edition of the textbook, my relationships with all of the supporting personnel has grown. Although the revision process is a heavy undertaking, the team at Pearson Higher Education has continued to make the experience not just manageable but actually enjoyable. Throughout the revision, I benefited from the expertise and hard work of many editors, reviewers, designers, production and marketing staff, and instructors. I extend to them my deepest and heartfelt thanks.

To begin, I want to acknowledge Frank Ruggirello, Serina ­Beauparlant, Barbara Yien, and Kelsey Churchman for their leadership and investment in this text. Thanks to my project and program managers, Chakira Lane and Chriscelle Palaganas, for their guidance during the work on this edition. Thanks to everyone involved in the book’s production and design development, particularly Nancy Tabor (production), Marilyn ­Perry (design manager), Emily Friel (interior designer), and Charlene Charles-Will (cover design). Thanks also to Tim Nicholls for handling the text and art permissions and Ashley Williams for coordinating reviews and numerous other tasks. In addition, I would like to thank Joe Mochnick for his work on the Mastering and media assets, a big part of this sixth edition. Thanks also to the Pearson marketing staff Allison Rona, Christy Lesko, and Jane Campbell.

In addition, I would like to express my thanks to the numerous reviewers and contributors who provided feedback on the prior edition and suggestions for this revision. Instructor comments are valued and seriously considered during each revision cycle. Please continue to send them!

I want to give a special thanks to Heather Wilson-Ashworth of Utah Valley University and Cheryl Neudauer of Minneapolis ­Community and Technical College for developing the Solve It ­activities.

There are no words that can express the gratitude I have for the support and encouragement of my wonderful husband Jim. Without him, there would be no text. I am also grateful to my colleague Robin Mockett who also utilizes the text and provides feedback. And a special thanks goes to Theresa Allsup, who keeps my life sane by running the prehealth advising office.