What is the composition of the ionosphere?

The ionosphere is primarily composed of free electrons and ions, which are formed when ultraviolet (UV) and X-ray radiation from the Sun ionizes atmospheric gases. The main gases present include nitrogen (N2) and oxygen (O2), along with trace amounts of other elements. The ionosphere is stratified into different layers (D, E, and F) based on altitude and ionization levels, with the F layer being the most densely ionized. This ionization plays a crucial role in radio wave propagation and affects various communication systems.