  Anisotropic flow phenomena is a key probe of the existence of Quark-Gluon
Plasma. Several new observable associated with correlations between anisotropic
flow harmonics are developed, which are expected to be sensitive to the initial
fluctuations and transport properties of the created matter in heavy ion
collisions. I review recent developments of correlations of anisotropic flow
harmonics. The experimental measurements, together with the comparisons to
theoretical model calculations, open up new opportunities of exploring novel
QCD dynamics in heavy-ion collisions.
