A five-day conference celebrating the legacy of Raoul Bott was held at the CRM on June 9-13, 2008. The conference focused on the extraordinary impact Bott had on both topology and interactions between mathematics, physics and technology. The conference was co-organized by the Clay Mathematics Institute and had support from the National Science Foundation (Award 0805925). Montreal was a natural venue for such an event since Raoul Bott obtained two degrees in electrical engineering at McGill University in the 1940s and an honorary doctorate from McGill in 1987. The fact that Bott's presence is still fresh in the minds of all those involved made for a tremendous amount of enthusiasm and every attempt has been made to channel this energy into this book. The contributions to this book come from three generations of Bott's students, coauthors, and fellow kindred spirits in order to cover six decades of Bott's research, identify his enduring mathematical legacy and the consequences for emerging fields. The contributions can be read independently. In order to help a whole to emerge from the parts, the book is broken into four sections and to make the book accessible to a wide audience, each section starts with easier-to-read reminiscences and works its way into more involved papers. Titles in this series are co-published with the Centre de Recherches Mathematiques. (CRMP/50).