In (ultra-)relativistic heavy-ion collisions, the strongly interactingmatter is predicted to undergo a phase transition into a plasma of deconfinedquarks and gluons (QGP) and quarkonia probe different aspects of this medium.However, the medium modification of quarkonium production includes also the contribution of cold nuclear matter effects (CNM), such as shadowing or nuclear break-up in addition to QGP effects. Proton--nucleus collisions, where no QGP is expected, are used to measure cold nuclear matter effects on quarkonium production. Vacuum production of quarkonia is modelled in proton--proton (pp) collisions, which are used as reference for both heavy-ion and proton--nucleus collisions. Besides serving as reference, results in pp collisions represent a benchmark test of QCD based models in both perturbative and non-perturbative regimes. The ALICE detector has unique capabilities at the LHC for measuring quarkonia down to zero transverse momentum. Measurements are carried out at both central and forward rapidity, in the dielectron and dimuon decay channel, respectively. In this contribution the latest quarkonium measurements for various energies and colliding systems, performed by the ALICE Collaboration during the LHC Run-2 period, will be discussed.
Quarkonium production and polarization in pp collisions with CMS