  As the formation of cosmic structure continues to proceed, we observe one of
the latest stages of this process in mergers of clusters of galaxies with other
clusters, groups, and galaxies. The X-ray emitting hot plasma of these systems
can be dramatically affected by these mergers, producing cold and shock fronts,
gas sloshing, bulk motions, and turbulence. Combined with numerical
simulations, observations of these features can be used to constrain the plasma
physics of the hot gas as well as its interaction with high-energy cosmic rays.
In this chapter, we review these topics and point forward to what the
capabilities of future observatories will reveal.
