The D Region, also known as the D layer, is a part of the Earth's atmosphere located between 30 to 90 miles above the surface. It is primarily composed of ionized particles and is influenced by solar radiation. This region plays a crucial role in radio wave propagation, affecting how signals travel through the atmosphere. In addition to its impact on communication, the D Region is also involved in the formation of the ionosphere, which is essential for various technologies, including GPS and satellite communications. Understanding the D Region helps scientists study atmospheric conditions and improve communication systems.