The Lyman-alpha emission line offers a powerful window into galaxies and their diffuse environments at high redshift. Observations from high-sensitivity instruments mounted on telescopes such as Subaru, HET, and JWST encode the distribution of hydrogen and the processes shaping its evolution. However, interpreting these data remains challenging due to the complex radiative transfer of the Lyman-alpha line. In this talk, I will present recent advances in theoretical and computational modeling of Lyman-alpha emitters, their extended halos, and the surrounding cosmic web. I will highlight implications for upcoming surveys and outline future directions aimed at uncovering the physical mechanisms that shape the observed signatures.