Laser beam propagation is the academic and research field dedicated to understanding how coherent optical radiation, specifically laser beams, travels through diverse media, including vacuum, atmosphere, and optical materials. This involves investigating the evolution of beam characteristics such as intensity distribution, phase, size, and divergence, and the influence of phenomena including diffraction, absorption, scattering, and nonlinear optical effects on the beam's properties over distance, which is fundamental to the design and performance of optical systems and technologies.