  Protoplanetary disks are the sites of planet formation, and the evolution and
eventual dispersal of these disks strongly influences the formation of
planetary systems. Disk evolution during the planet-forming epoch is driven by
accretion and mass-loss due to winds, and in typical environments
photoevaporation by high-energy radiation from the central star is likely to
dominate final gas disk dispersal. We present a critical review of current
theoretical models, and discuss the observations that are used to test these
models and inform our understanding of the underlying physics. We also discuss
the role disk dispersal plays in shaping planetary systems, considering its
influence on both the process(es) of planet formation and the architectures of
planetary systems. We conclude by presenting a schematic picture of
protoplanetary disk evolution and dispersal, and discussing prospects for
future work.
