Ionized cluster Beams (ICB) are widely used to deposit metal, semiconductor and insulating films. The paper describes the current state of this technology in both fundamental and applications areas. One important ambiguity in the theory of metal cluster formation is addressed. RBS is used to measure the extent of any displacement of surface atoms caused by ICB. The minimal amount of such surface damage is confirmed by the close-to-ideal values measured for Schottky barrier height on an Al/Si interface. Several examples of ICB application are described.