Heavy quarks, charm and beauty, can be created only in hard scattering in the first instants after the collisions and, therefore, they are a powerful tool to investigate the properties of the Quark Gluon Plasma created in heavy-ion collisions. In ALICE, open charm production is measured through the full reconstruction of D-meson hadronic decays at mid-rapidity. In this talk I will discuss the measurements of D-meson production in different collision systems, focusing on LHC Run 2 results.