  We discuss, in this review, the existing models for the production of QGP in
Relativistic Heavy Ion Collisions. We shall try to give a brief description of
the models available for the pre-equilibrium production of QGP, ranging from
soft process dominated QCD regime to the pQCD dominated regime. We also present
the estimates for the initial energy density, the temperature and the
thermalisation time -- available from each of these studies. Finally, we shall
address the questions regarding thermalisation, color equilibration and
chemical equilibration of the produced QGP in different experimental
facilities.
