Towards the quark-gluon plasma

We discuss recent experimental results in the field of ultra-relativistic n uclear collisions. The emerging "picture" is a collectively expanding, init ially hot and dense fireball in which strangeness- and low-mass di-lepton p air production are enhanced and J/Psi production is suppressed compared to expectations from nucleon-nucleon collisions. It is argued that, taken toge ther, these data provide circumstantial evidence that a (at least partly) p artonic phase was produced in such collisions.