My editor, Lorrie LeJeune, deserves special thanks for her work in developing the bioinformatics titles at O'Reilly. Her level of expertise is rare in any field. I thank Lorrie, Tim O'Reilly, and their colleagues for making it possible to bring these books to the public. I thank my technical reviewers for their invaluable expert help: Joel Greshock, Joe Johnston, Andrew Martin, and Sean Quinlan. I also thank Dr. Michael Caudy for his helpful suggestions in Chapter 3. I thank again those individuals mentioned in the first volume, especially those friends who have supported me during the writing of this book. I am also grateful to all those readers of the first volume who took the time and trouble to point out errors and weaknesses; their comments have substantially improved this volume as well. I thank Eamon Grennan and Jay Parini for their patient help with my writing. And I especially thank my much-loved children Rose, Eamon, and Joe, who are my most sincere teachers.