Heavy ions at CMS

n the present proceedings recent heavy ion results from the CompactMuon Solenoid collaboration at the LHC are presented. These contain comparisonsbetween small and large collision systems, as well as studies of energy evolution, andthus include data collected in proton-proton collisions at 13 TeV (2015 and 2016),proton-proton and lead-lead collisions at 5 TeV (2015), and proton-lead collisions at5 TeV and 8 TeV (2016) center-of-mass energy per nucleon pair. They provide newinsights into the properties of the extremely high density and high temperature mat-ter created in heavy ion collisions, while pointing out similarities and differences incomparison to smaller collision systems. These include gluon distribution functionsin the lead nucleus; the azimuthal anisotropy of final state particle distributions inall the three different collision systems; charge separation signals from proton-leadcollisions and consequences for the Chiral Magnetic Effect; new studies of partonenergy loss and its dependence on parton flavor and parton shower shape; and thesuppression of quarkonium states in the deconfined QCD matter.