The same amount of energy that is released from the system should return to the system in a specific form to reverse the process. For this to happen, we need to compensate the energy of the system to the same amount that it was before the forward process began at the initial equilibrium state. From thermodynamic equations, one perceives in a spontaneous process part of the energy is lost as dissipated work. During the transfer of energy to the system from surrounding, the entropy of the system increases more than the heat that is absorbed by the system such that in the system Q -T ∆S < 0. The increase of the entropy of the system that is rooted in the increase in the chaosity of the system leads to the expansion work of -p∆V in the system when the degrees of freedom colloid with the system's boundaries. In an irreversible process, we should compensate for the dissipated heat and useful work to reverse the direction of the process. Therefore, in a cyclic irreversible process as the system returns to its initial state, the net change of entropy of the system is zero. On the other hand, the total entropy change of the universe in an irreversible process is larger than zero. This means even though the entropy of the system stays constant, the entropy of the surrounding, and therefore universe in a real system increases.