  Jets are expected to play a prominent role in the ongoing efforts to
characterize the hot and dense QCD medium created in ultrarelativistic heavy
ion collisions. The success of this program depends crucially on the existence
of a full theoretical account of the dynamical effects of the medium on the
jets that develop within it. By focussing on the discussion of the essential
ingredients underlying such a theoretical formulation, we aim to set the
appropriate context in which current and future developments can be understood.
