  We discuss two themes from Chandra and XMM-Newton observations of galaxies,
groups, and clusters. First, we review observational aspects of cluster
formation and evolution as matter accretes along filaments in A85 and A1367. We
describe Chandra observations that probe the later evolutionary phases where
the effects of mergers -- both subsonic and supersonic -- are observed in
cluster cores as ``cold fronts'' and shocks. Second, we review the interactions
between the hot, intracluster gas with relativistic plasma originating in
active nuclei within the dominant galaxy at the cluster center. As examples of
this interaction, we describe the radio and X-ray observations of M87 where
buoyantly rising bubbles transfer energy and matter within the cluster core. We
describe the Chandra observations of ZW3146 which exhibits both multiple cold
fronts and relativistic plasma interactions. Finally, we describe the X-ray
observations of NGC4636 where energy produced by the central AGN imprints a
unique signature on the surrounding hot corona of the galaxy.
