In 1967 Partridge and Peebles theorized that young galaxies at high redshifts emitting Lyman-α photons might be a suitable tracer of large-scale structure. Those distant galaxies of high Lyman-α emission, so-called Lyman Alpha Emitters (LAEs) can be used to constrain the cosmological standard model at high redshifts and furthermore allow insight for the environment of those galaxies. The Lyman-α line corresponds to the energy difference from the ground state to the first excited state of neutral hydrogen.