The 23rd edition of Rudolph’s Pediatrics was made possible by the creative input and hard work of an outstanding team of co-editors from the Department of Pediatrics at Texas Children’s Hospital and Baylor College of Medicine, including Susan Blaney, Angelo Giardino, Jordan Orange, Dan Penny, Gordon Schutze, and Lara Shekerdemian. Abraham Rudolph and Colin Rudolph provided invaluable perspective and input during the planning phase of textbook production. All of us are indebted to the 44 section editors and 845 authors who contributed to this 2950-page textbook. We also are indebted to Julie O’Brien, Mark Meyer, and Lee Ligon at the Texas Children’s Hospital and Baylor College of Medicine for administrative support and editorial assistance, and to Andrew Moyer, Tania Andrabi, and the entire editorial staff at McGraw-Hill for their partnership, support, and guidance. I want to thank my longtime friend Smiley Pool for the stunning cover photography. Finally, special thanks to Sandra Queen for allowing us to use the photograph of her darling and much loved late daughter Janie in the swimming pool.