Symmetry breaking is partially responsible for the astounding variety of natural phenomena derived from a few simple and symmetric basic laws. Unique in its multidisciplinary scope, this book considers from a unified point of view the structure and dynamics of vortices in a variety of nonlinear field models with spontaneously broken symmetry. The theory has wide applications, including superfluids, superconductors, rotating spiral waves, and relativistic string theories. This volume is an integrated survey of this rapidly developing field.