2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/4819It is now ten years since the first microquasar GRS 1915+105 was discovered. More than six years of observations with RossiXTE have shown a level of variability never observed in any other X-ray source. Here I try to address some issues, based on X-ray observations only, that have relevance for theoretical modeling. First, I ignore these peculiarities and concentrate on the similarities with other X-ray transients. Then I focus on the peculiar variability and present a number of obervational facts that need to be addressed by theoretical models.8 pages, 8 figures; to appear in Proceedings of the 4th Microquasar Workshop, eds. Ph Durouchoux, Y. Fuchs and J. Rodriguez, published by the Center for Space Physics: KolkataAstrophysicstext