Based on many years of research, a theory of gas dynamics of combustion, explosion, and detonation processes was developed. However, the fundamental problems of their chemical and physicochemical characteristics began to be solved only in the last two or three decades. The cardinal problem in gas combustion is the discovery of the physicochemical mechanism of these rapid processes, which occur despite the strong chemical bonds of molecules. A brief citation of some of the basic principles of chemical kinetics, mostly known to readers, is intended to make the book easier to read. The current ideas about the role of activation energy in the temperature dependence of reaction rates are briefly analyzed. Several important patterns of combustion reactions that contradict previously generally accepted ideas are pointed out. The impossibility of combustion of gases in reactions of only valence-saturated molecules is proven on the basis of their very high activation energies. Previously unknown important patterns of combustion considered in the book are presented.