The paper reviews the most important contributions in the area of the coaIs chemistry and physics. In particular, discussed are hypotheses on the character of the coaIs structure unit and on two- and three-dimensional structural models of coal. Processes and chemical reactions taking place during carbonization are presented. This is folIowed by the compilation of the available polymeric models of the coal's structure. Recent studies on coal as a two-component system are discussed including such problems as the chemical structure of the molecular and macromolecular components, interactions between these two components, and chemical character and density of cross-linked bonds in the macromolecular framework. In the subsequent chapter, studies on coaI as a colloidal system are described with emphasis on changes in the coal's colloidal structure during carbonization. Numerous investigations concerning the physicaI structure of coaI and its changes during carbonization are, too, addressed. The review leads to a conclusion that the availabIe structural models are not alternatives but they are rather complementary to each other. By including both the chemical and physical approaches to the coals structure a better understanding of many structural aspects and a more realistic description of the coal's behavior during carbonization can be achieved.