I have had the good fortune to work with many talented and caring people who have shared their knowledge and helped shape my thinking in this area. First and foremost, I want to thank the late Norman A. Marlow who gave me the freedom to pursue interesting and important problems in network and service reliability and guided my early career at Bell Laboratories. Elsayed A. Elsayed and Endre Boros promoted my pleasant and fruitful relationship with Rutgers University. Many other colleagues and friends contributed their time and expertise to help me learn more about reliability engineering. These include Susan Albin, Sigmund J. Amster, Lawrence A. Baxter, Michele Boulanger, Chun Kin Chan, Ramon V. Leon, Michael LuValle, and William Q. Meeker. José Ramirez-Marquez helped me pass the torch. Working with Bill Frakes on the SUPER project was an education and a pleasure. A. Blanton Godfrey, Jeffrey H. Hooper, and William V. Robinson provided invaluable management support, and Jon Bankert and Jack Sipress gave me an opportunity to work with the Bell Labs Undersea Cable Laboratory where I learned a great deal of practical reliability engineering. I am grateful to Stevens Institute of Technology for employing me to teach a course in the Systems Engineering program based on these ideas. I am deeply grateful to Chun Kin Chan, Bill Frakes, and D. A. Hoeflin for carefully reading the manuscript and offering excellent suggestions. I have also benefitted from conversations with David Coit, Elsayed Elsayed, Shirish Kher, Mohcene Mezhoudi, Himanshu Pant, William V. Robinson, and Terry Welsher. Outside my immediate circle of colleagues, I thank Harry Ascher, Alessandro Birolini, Ilya Gertsbakh, and William A. Thompson. Learning from their clear and well-constructed books helped me be a better reliability engineer. Laura Madison helped clean up my sometimes too-convoluted prose; her patience in taking on a bigger job than she anticipated is much appreciated. Finally, my thanks to Andrea for her patience with my frequent and extended disappearances into the authorial vortex. To all these and many more too numerous to mention, thank you for helping shape this book. I have tried to learn from your suggestions, but people tell me I am sometimes a stubborn cuss, so there may remain errors in the book, and if so, they are mine alone.