The purpose of this review is to show how the development of ideas regarding classical fluctuations in a system of charged particles initially led to an understanding of the nature of collective collisions of particles, transition scattering, and transition bremsstrahlung and also to an understanding of why the cross sections for emission and scattering in a system of many particles are fundamentally different from those for individual charged particles. It is then shown how the development of these concepts and their generalization to the relativistic and quantum-mechanical cases necessarily lead to the appearance of collective radiative-resonant interactions.