  The known exoplanet population displays a great diversity of orbital
architectures, and explaining the origin of this is a major challenge for
planet formation theories. The gravitational interaction between young planets
and their protoplanetary disks provides one way in which planetary orbits can
be shaped during the formation epoch. Disk-planet interactions are strongly
influenced by the structure and physical processes that drive the evolution of
the protoplanetary disk. In this review we focus on how disk-planet
interactions drive the migration of planets when different assumptions are made
about the physics of angular momentum transport, and how it drives accretion
flows in protoplanetary disk models. In particular, we consider migration in
discs where: (i) accretion flows arise because turbulence diffusively
transports angular momentum; (ii) laminar accretion flows are confined to thin,
ionised layers near disk surfaces and are driven by the launching of
magneto-centrifugal winds, with the midplane being completely inert; (iii)
laminar accretion flows pervade the full column density of the disc, and are
driven by a combination of large scale horizontal and vertical magnetic fields.
