Thermophysical bases of vitrification and crystallization are discussed in terms of the enthalpy versus temperature diagram and its derivative (DTA) illustrating relaxation and glass transformation as well as crystallization of glassy and amorphous states to form stable and metastable phases. Non-isothermal kinetics are thoroughly discussed and the use of one-(JMAEK) and two-(SB) parameter equations is described. The practical case of the complementary 70SiO(2)-10Al(2)O(3)-20ZnO glass treatment is demonstrated for both standard nucleation-growth curves and corresponding DTA recordings; these show a good coincidence of the activation energies obtained.