Plasma carburizing (ion carburizing) is a carburizing method which offers both economic and technological advantages over conventional methods. It utilizes the properties of an anomalous glow discharge and is explained in detail on the basis of a representation of the principle of operation, examples of furnaces, and applications. Product- and process-specific advantages, such as good wear properties, clean product surface, good control of the process parameters, rapid carburization, carburization at narrow gaps and boreholes, decarburization-free diffusion treatment, low distortion, low process gas consumption and high carburization efficiency, are demonstrated.