Approaching the Final State in Perturbative QCD

Infrared safe differential cross sections, such as event shape distributions, can be measured over wide kinematic ranges, from regions where fixed order calculations are adequate to regions where nonperturbative dynamics dominate. Such observables provide an ideal laboratory for the study of the transition between weak and strong coupling in quantum field theory. This talk focuses on how resummed perturbation theory has been used to deduce the structure of nonperturbative corrections, and to provide a framework with which to address the transition from short- to long-distance dynamics in QCD.