This book is devoted to the applications of the mathematical theory of solitons to physics, statistical mechanics, and molecular biology. It contains contributions on the signature and spectrum of solitons, nonlinear excitations in prebiological systems, experimental and theoretical studies on chains of hydrogen-bonded molecules, nonlinear phenomena in solid-state physics, including charge density waves, nonlinear wave propagation, defects, gap solitons, and Josephson junctions. The content is interdisciplinary in nature and displays the new trends in nonlinear physics.