  The productions of real photons from quark gluon plasma and hot hadronic
matter formed after the nucleus - nucleus collisions at ultra-relativistic
energies are discussed. The effects of the spectral shift of the hadrons at
finite temperature on the production of photons are investigated. On the basis
of the present analysis it is shown that the photon spectra measured by WA98
collaboration in Pb + Pb collisions at CERN SPS energies can be explained by
both QGP as well as hadronic initial states if the spectral shift of hadrons at
finite temperature is taken into account. Several other works on the analysis
of WA98 photon data have also been briefly discussed.
