This volume summarizes our contemporary understanding of the deconfinement transition in QCD at finite temperature and chemical potential. Questions as to whether a quark-gluon plasma exists in the interior of dense astrophysical objects or which bound-state signals have to be studied in order to unambiguously detect the QCD phase transition(s) in future heavy-ion collision programmes at RHIC and LHC are addressed. Progress in answering these questions requires a fusion of lattice QCD with other nonperturbative approaches and low-energy effective models for QCD. Experts in these fields present in the book their methods and their results in understanding the deconfinement phenomenon.