Quarkonium in ALICE: results on p-Pb and Pb-Pb collisions from LHC Run 2

<!--HTML--><p>In 1986, the modification of quarkonium production was first proposed as a signature of the formation of a Quark Gluon Plasma.&nbsp;While the central role of quarkonium in the understanding of the QGP is indisputable, the direct link between the expected sequential suppression,&nbsp;in a very hot medium, and the experimental observations is not yet completely settled.&nbsp;Several other mechanisms, related to either the formation of a hot medium, such as quarkonium regeneration, or to the presence of&nbsp;cold nuclear matter, are well-known key effects in the interpretation of the results.</p> <p>This talk reviews very recent LHC Run 2 results obtained with the ALICE detector, which is designed to study quarkonium in two rapidity ranges, &nbsp;at mid-rapidity ($|y|&lt;0.9$) in the dielectron decay channel and at forward rapidity ($2.5&lt;y&lt;4$) in the dimuon channel, both down to zero transverse&nbsp;momentum.&nbsp;Results on the J/$\psi$ nuclear modification factor ($R_{\rm{AA}}$) and azimuthal anisotropy, measured, with high precision, at the highest LHC&nbsp;Pb-Pb energy ($\sqrt{s_{\rm{NN}}}$= 5.02 TeV), will be presented. Results on the other quarkonium states as the loosely&nbsp;bound $\psi(2S)$ and the heavier bottomonium resonances will also be addressed.&nbsp;The impact of these measurements on our understanding of quarkonium production, absorption and regeneration in the hot QCD matter&nbsp;will be discussed by comparing both to results from lower energies and to theoretical predictions.&nbsp;Finally, results on $J/\psi$ production in p-Pb collisions at $\sqrt{s_{\rm{NN}}}$= 8.16 TeV will also be presented and compared to models including&nbsp;different sources of cold nuclear matter effects.</p>