Lyman-alpha emission is a term used in astrophysics to describe a specific spectral line in the ultraviolet region of the electromagnetic spectrum. The Lyman-alpha emission line is associated with the transition of an electron in a hydrogen atom from the first excited state (n=2) to the ground state (n=1). This transition results in the emission of a photon with a wavelength of 121.6 nanometers. Studying Lyman-alpha emission is important in understanding the properties and dynamics of neutral hydrogen gas in the interstellar medium, as well as in galaxies and quasars. It can provide valuable information about the processes of ionization, recombination, and cooling of gas in these regions. Observations of Lyman-alpha emission can also help astronomers to study the formation and evolution of galaxies, as well as to probe the intergalactic medium and detect high-redshift objects. Overall, research on Lyman-alpha emission plays a crucial role in advancing our understanding of the universe and its components.