The theory of electromagnetic radiation generated by a fast charged particle passing at a constant velocity through a uniform medium (the Vavilov-Cherenkov radiation), a non-uniform medium (the transition radiation), or a single crystal (the quasi-Cherenkov radiation) is briefly reviewed. Several main experimental results and the applications in constructing high-energy particle detectors are discussed. The hard radiation emitted by charged particles moving in a crystal at small angles relative to crystallographic axes and planes in the regime of channeling or quasichanneling and the influence of particles incoherent scattering are also discussed.