Nonperturbative QCD and Quark-Gluon plasma

This is a brief written version of 5 lectures made at 2001 ICTP Summer School on High Energy Physics in Triest. The lectures provide an overview of what we have learned about QCD vacuum, hadrons and hot/dense hadronic matter during the last 2 decades. Last two lectures contain discussion of heavy ion physics. We focus on the first surprising results from new heavy ion collider, RHIC, as well as recent development toward understanding of the old problem of "soft pomeron" in high energy hadronic collisions and its connection to new heavy ion data.