This work is devoted to the physical properties of non-ideal plasma which is compressed so strongly that the effects of interparticle interactions govern the plasma behaviour. The interest in this plasma was generated by the development of modern technologies and facilities whose operations were based on high densities of energy. In this volume, the methods of non-ideal plasma generation and diagnostics are considered. The experimental results are given and the main theoretical models of non-ideal plasma state are discussed. The problems of thermodynamics, electro-physics, optics and dynamic stability are covered.