For the past few decades physicists have used the tools of quantum field theory to study the high energy, small-scale structure of the universe. Two promising candidates, string theory and supersymmetry, have also emerged as possible essential ingredients of a unified theory of all fundamental interactions. Most of our understanding of these areas has been obtained using perturbation theory which by construction is a largely incomplete description of a quantum theory. Many of the outstanding questions in theoretical physics such as the dynamics of quarks inside a nucleus, the full quantum nature of black holes, or the origin of our 4-dimensional spacetime will probably be answered only when we have complete non-perturbative formulations of the theories that we use to study them... What is remarkable is that much of the recent progress in understanding non-perturbative aspects of string theory and supersymmetric gauge theories has been made in parallel, using each to gain knowledge and..