The ejection of material from a solid or liquid surface following the impact of energetic ions, atoms, or molecules. Sputtering was first noted in 1853 by W. R. Grove and in 1854 by M. Faraday as the occurrence of a metallic coating on the glass walls of a discharge tube. E. Goldstein in 1902 showed that the sputtering effect was caused by positive ions of the discharge striking the cathode and ejecting cathode material. Sputtering now is the basis of a large variety of methods for the synthesis and analysis of materials.