The textbook covers the classical material of technical thermodynamics in a compact form. In the initial chapters, the fundamental thermodynamic concepts of system, state variable, process variable, thermal equilibrium, and temperature are introduced. The first law of thermodynamics, discussed subsequently as the thermodynamic equivalent of energy conservation, allows for a clear definition of work, heat, internal energy, and enthalpy in its various formulations. The model system of the ideal gas enables the derivation of thermal and caloric equations of state and leads to the second law of thermodynamics, which expresses the principle of irreversibility of thermodynamic processes and motivates the concept of entropy. The following chapters deal with thermodynamic cycles with and without phase changes, using both ideal and real substances.