2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/62898We introduce a generalization of representations of quivers that contains also representations of posets, vectorspace problems and other matrix problems. Many examples, some of which are given in the paper, show that the language of marked quivers is rather convenient and that the notion of their representations can probably be considered as basic for a general theory of matrix problems. Some historical comments from my personal point of view are added in the Appendix.20 pages, accepted for publication in the Proceedings of ICRA IXRepresentation TheoryCategory TheoryRings and Algebrastext