Newton's laws are the foundation of classical mechanics; they allow the description of various types of motion, including propagation of waves in the acoustic and elastic media. To express physical laws in formulas that define the behavior of gravitational, electric, and magnetic fields, the concepts of elementary masses, charges, and currents are used. In this context, the chapter introduces the concept of an elementary mass (particle) and describes Newton's laws. This elementary mass is assumed to be uniformly distributed within a particle, and the particle's size is so small that all portions of its volume have the same velocity and acceleration at each instant. Such an assumption implies negligible influence of wave propagation within a particle and the absence of rotation of this mass around itself. The formulations of Newton's laws of mechanics, which apply to the elementary mass, are also presented in the chapter.