Signatures of quark-gluon plasma phase transition in high-energy nuclear collisions

In high-energy nuclear collisions, the new phase of the quark-gluon plasma is indicated by an anomalous increase in pressure, an excess of direct photon production, an excess of strangeness production, and an anomalous J/ psi suppression. We review these signatures and discuss how recent high-energy heavy-ion experiments at CERN are consistent with the production of the quark-gluon plasma in high- energy Pb+Pb collisions. (31 refs).