In any study of the properties of materials, it is obviously crucial to include the effect of anharmonicity at an extreme environment, which is accompanied by the changes in the elastic, vibrational and mechanical properties. There are two issues to be resolved when trying to compute the properties of metals at finite temperatures and pressures: first is how to describe the inter-atomic interactions of statistical nature accurately, and second is how to incorporate the effects of expansion and compression into this description. As for computing the effects of temperature and pressure, in principle, any of the first principles methods can be used. Unfortunately, though these ab initio methods are physically robust, they show some practical difficulties at high temperatures and pressures, and are relatively cumbersome too. In this view, results of ab initio methods at ambient conditions are combined to finite temperature methods such as mean-field theory to estimate complete thermodynamics of materials at high-T,P conditions. The present monograph is the illustration of the same, with special reference to metals.