Ultrarelativistic nuclear collisions at RHIC and the LHC recreate the hot, dense and coloured state of matter that prevailed in the early Universe from 10^-12 to 10^-6 seconds after the BIg Bang.

Our understanding of this QCD medium, the most perfect fluid ever observed in Nature, has greatly advanced in recent years. The extensive kinematic reach and excellent detection capabilities of the LHC combined with significant theoretical developments create the necessary conditions for the detailed probing of the properties of the medium.

Jets, the result of QCD branching of hard partons produced in the collisions, that develop within the medium are of particular relevance in this probing programme. After a general introduction to the physics of medium-induced modifications of jets (jet quenching), I will overview key recent theoretical developments.