  We review recent progress in the study of parton propagation, interaction and
fragmentation in both cold and hot strongly interacting matter. Experimental
highlights on high-energy hadron production in deep inelastic lepton-nucleus
scattering, proton-nucleus and heavy-ion collisions, as well as Drell-Yan
processes in hadron-nucleus collisions are presented. The existing theoretical
frameworks for describing the in-medium interaction of energetic partons and
the space-time evolution of their fragmentation into hadrons are discussed and
confronted to experimental data. We conclude with a list of theoretical and
experimental open issues, and a brief description of future relevant
experiments and facilities.
