Clusters of Galaxies: Diagnostic Tools for Cosmology
  Clusters 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. 
Sabine Schindler (Liverpool JMU)