Underlying event and correlation results from CMS

The underlying event activity in $pp$ collisions is measured using events with a leading charged-particle jet. The activity is measured independently in the two halves of the region transverse to the leading object, containing the maximum and minimum activities. Complementary to the underlying event analysis, the observation of long-range two-particle correlations in high energy heavy ion collisions opens opportunities to explore QCD in quark gluon plasma, the hot dense matter created in heavy ion collisions. The observation of similar correlation structures in high multiplicity $pp$ collisions suggests novel QCD effects. We present selected results of the underlying event activity and particle correlations in various collision systems.