2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/1859Clusters of galaxies can be used for very different kinds of cosmological tests. I review a few of the methods: determination of cluster masses and dark matter content, metal enrichment and its connection to the origin of the intra-cluster gas, and the dynamical state of clusters. The progress in the different fields expected from observations with the new X-ray satellites XMM and Chandra is pointed out.9 pages, 5 figures. Review presented at the Vulcano Workshop 2000, Frontier Objects in Astrophysics and Particle Physics, F. Giovannelli, G. Mannocchi (eds.)Astrophysicstext