2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/203535Dileptons provide direct observables of the electromagnetic current-current correlator in the hot and/or dense medium formed in heavy-ion collisions. In this article an overview is given about the status of the theoretical understanding of the dilepton phenomenology in heavy-ion collisions from studies of the in-medium properties of hadrons and partons within many-body theory and about connections to fundamental questions concerning the chiral phase transition.8 pages, 2 figures, contribution to the proceedings of the 20th International Conference on Ultra-Relativistic Nucleus Nucleus Collisions (Quark Matter 2008); v2: Version accepted for publication at J. Phys. GHigh Energy Physics - Phenomenologytext