The talk will focus on the interaction between
the gaseous protoplanetary disc and embedded solid bodies
such as planetesimals, low mass protoplanets, and
forming gas giant planets. I will review the basic
results that apply when the disc has a simple laminar
structure, and discuss the results of recent simulations
that examine what happens when the disc supports MHD turbulence.
I will also present the results of recent simulations that
model the formation of terrestrial planets during the
migration of gas giant planets through the habitable zone.