  Groups and clusters contain a large fraction of hot gas which emits X-ray
radiation. This gas yields information on the dynamical state and on the total
mass of these systems. X-ray spectra show that heavy elements are present in
the gas. As these metals must have been produced in the cluster/group galaxies
and later transported into the gas, the metallicity is a good tracer for the
transport processes. Several possible processes, that transport gas from the
small potential wells of the galaxies into the clusters and groups, are
discussed.
