It has now been nearly ten years since the successful publication and enthusiastic reception of RF Superconductivity for Accelerators. Much has happened in the field since the appearance of this work, which is heavily referenced as a standard text. There has been an explosion in the number of accelerator applications and in the number of laboratories engaged in the field. RF superconductivity has become a major subfield of accelerator science. The overall aim of this book is to discuss advances in the science, technology, and applications of superconducting rf (SRF) since the 1998 publication.