  The first detection of a diffuse radio source in a cluster of galaxies, dates
back to the 1959 (Coma Cluster, Large et al. 1959). Since then, synchrotron
radiating radio sources have been found in several clusters, and represent an
important cluster component which is linked to the thermal gas. Such sources
indicate the existence of large scale magnetic fields and of a population of
relativistic electrons in the cluster volume. The observational results provide
evidence that these phenomena are related to turbulence and shock-structures in
the intergalactic medium, thus playing a major role in the evolution of the
large scale structure in the Universe. The interaction between radio sources
and cluster gas is well established in particular at the center of cooling core
clusters, where feedback from AGN is a necessary ingredient to adequately
describe the formation and evolution of galaxies and host clusters.
