  The hot and dense matter formed in relativistic heavy-ion collisions at
Relativistic Heavy Ion Collider (RHIC) and Large Hadron Collider (LHC) is
termed quark-gluon plasma (QGP). The evolution of the medium is characterized
by non-trivial velocity and vorticity fields, resulting in the polarization of
the produced particles. The spin polarization, being sensitive to the
hydrothermal (flow velocity and temperature) gradients, is unique compared to
conventional observables that are sensitive to the hydrothermal fields only.
Hence, the recent measurements of global and local hyperon spin polarization
and vector meson spin alignment by the LHC and STAR collaborations provide a
unique opportunity to probe the QGP substructure with finer details.
