Heavy-ion collision experiments provide unprecedented access to the physics of the deconfined phase of QCD, the quark-gluon plasma. A crucial part of this program is using the modified properties of jets in heavy-ion collisions as a probe of the plasma they pass through. I will give a brief introduction on the theory and modelling of parton energy loss and jet modification in the quark-gluon plasma. I will then discuss a data-driven method to measure the separate modification of quark- and gluon-initiated jets in the quark-gluon plasma.