Path loss refers to the reduction in power density of a signal as it travels through space. This phenomenon occurs due to various factors, including distance, obstacles, and environmental conditions. As a signal moves away from its source, it loses strength, which can affect communication quality. Several factors contribute to path loss, such as free space loss, reflection, refraction, and diffraction. These elements can cause the signal to scatter or absorb, leading to weaker reception. Understanding path loss is crucial for designing effective communication systems, including cellular networks and Wi-Fi.