The last few years have seen many developments in the study of "frustrated" systems, such as spin glasses and random fields. In addition, the application of the idea of spin glasses to other branches of physics, such as vortex lines in superconductors, protein folding and the vulcanization of rubber, has been flourishing. The articles in this book have been written by leading researchers and include theoretical and experimental studies, large-scale numerical work (using state-of-the-art algorithms designed specifically for spin-glass-type problems), as well as analytical studies.