In this introductory chapter, we present a short summary of the historical development of thermodynamics, discuss briefly its place in science and importance for the mankind. The beginning of thermodynamics can be associated with the first attempts to measure temperature, made probably by Galileo at the end of the 16th century. The first barometer was constructed by Torricelli some 50 years later. One of the milestones in the development of thermodynamics was the discovery of conversion of work into heat and vice versa, associated mainly with the names of Watt and Carnot, and the discovery of the absolute temperature scale by Thomson (Lord Kelvin) in the middle of the 19th century. About the same time Helmholtz extended the energy conservation principle to all branches of physics and Clausius introduced the concept of entropy and formulated the second law of thermodynamics. The remaining two laws of thermodynamics, the third and zeroth laws, were formulated by Nernst and Carathéodory, respectively, in the first decade of the 20th century.