These lectures are devoted to a review of the contemporary high energy density physics. Pre-quark models and the quark conception are briefly treated, and a sketch of quantum chromodynamies is given. Semi-phenomenological models of hadron matter under extreme conditions are then described, i.e. lattice calculations, quark-gluon bag model, hydrodynamic theory of multiple production, and experiments to detect signals of quark-gluon plasma formation, the last lecture looks at confinement criteria, thermodynamics of the quantum field model with confinement (QED3), and the question of whether there is deconfinement in this model.