2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/65685In this survey article, we recall some facts about split Kac-Moody groups as defined by J. Tits, describe their main properties and then propose an analogue of Borel-Tits theory for a non-split version of them. The main result is a Galois descent theorem, i.e. the persistence of a nice combinatorial structure after passing to rational points. We are also interested in the geometric point of view, namely the production of new buildings admitting (nonuniform) lattices.45 pages, 9 figuresGroup Theory22E20, 51E24, 17B67, 22F50, 22E40text