In this work, interference and coherence phenomena, appearing in atomic and molecular ensembles interacting with coherent light sources, as electromagnetically induced transparency (EIT), coherent population trapping (CPT), and slow group velocity of light are investigated. The goal of the project is to make the steps towards various applications of these phenomena, first, by studying them in solid media (which are the most advantageous for applications), second, by suggesting some novel applications such as CPT-based plasma diagnostics, and realization of new types of solid-state lasers (based on suppression of excited-state absorption via EIT). The third goal of the project is extension of coherence and interference effects well-known in optics to the gamma-ray range of frequencies and, correspondingly, from atomic to nuclear transitions. A particular technique of chirped pulse compression applied to M??ossbauer transitions is considered and the possibility of compression of M??ossbauer radiation into ultrashort gamma-ray pulses is analyzed. The theoretical treatment of the interference and coherence effects is based on the semiclassical description of atom-light interaction, which is sufficient for correct analysis of the phenomena considered here. Coherent media are considered in two-, three-, and four-level approximations while their interaction with light is studied both analytically and numerically using the Maxwell-Bloch set of equations.