Problems of reemission and reabsorption in Nonlinear and Relaxed Optics are discussed. It was shown that these processes and corresponding phenomena are connected with processes of first order absorptive excitations in irradiated matter and second order relaxation of these excitations. Nature of this relaxation stipulated Nonlinear Optical phenomena for case of radiated relaxation and Relaxed Optical phenomena for case of radiationless relaxation. Basic peculiarities of these processes and methods of its modeling are analyzed and discussed.