2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/1297391) Introduction 2) PopIII stars and galaxies: a "top-down" theoretical approach 3) Lyman-alpha physics and astrophysics 4) Distant/primeval galaxies: observations and main results48 pages including figures. Lecture notes to appear in "The emission line Universe", XVIII Canary Islands Winter School of Astrophysics, Ed. J. Cepa, Cambridge Univ. PressAstrophysicstext