The "E Layer," also known as the E-region, is a part of the Earth's ionosphere, located approximately 90 to 150 kilometers above the surface. This layer is characterized by the presence of free electrons, which are created when solar radiation ionizes the gases in the atmosphere. The E Layer plays a crucial role in radio wave propagation, as it can reflect certain frequencies back to the Earth's surface. The E Layer is influenced by solar activity, such as solar flares and coronal mass ejections, which can enhance its ionization levels. This layer is typically more active during the daytime and can affect communication systems, including shortwave radio and GPS, by altering signal paths.