The word “Thermodynamics” originates from its Greek roots (therme, heat; dynamis, force). As a subject it is concerned with quantification of the inter-relation between energy and the change of state of any real world system. The extent of such change of state due to transfer of energy to or from the system is captured through the basic equations of thermodynamics which are derived starting from a set of fundamental observations known as “Laws of Thermodynamics”. The laws are essentially ‘postulates’ that govern the nature of interaction of real systems and energy. They are products of human experiential observations to which no exceptions have been found so far, and so are considered to be “laws”. The scope of application of the laws of thermodynamics ranges from the microscopic to the macroscopic order, and indeed to cosmological processes. Thus, all processes taking place in the universe, whether in non-living or living systems, are subject to the laws of thermodynamics.