This is a self-contained collection of reviews, reports and survey articles describing the background to and recent developments in integral systems and their applications in modern theoretical physics. Some articles discuss the connection of integrable models to Seiberg-Witten theory and its generalization to many gauge models possessing hidden integrability on a moduli space. New ideas are also presented on higher dimensional integrable systems and skyrmions.Other topics covered herein include two dimensional sigma and WZW models; affine and boundary integrable Toda field theories and related perturbed conformal quantum field theories; boronic and supersymmetric, discrete and differential KP and Toda-type hierarchies, their various symmetry reductions, boronic and fermionic, isospectral and non-isospectral, local and non-local flows; trigonometric Calogero-Moser systems; conjugate, orthogonal and Egorov nets. This book offers an unique insight into integrable models that will interest serious practitioners, young researchers and graduate students starting their careers in the area.