Plasma source ion implantation (PSII) with metal plasma results in a qualitatively different kind of surface modification than with gaseous plasma due to the condensable nature of the metal plasma, and a new, PSII-related technique can be defined : metal plasma immersion ion implantation and deposition (MPI). Tailored, high-quality films of any solid metal, metal alloy, or carbon (amorphous diamond) can be formed by MPI using filtered vacuum arc plasma sources, and compounds such as oxides or nitrides can be formed by adding a gas flow to the deposition. Here we describe the plasma formation at cathode spots, macroparticle filtering of the vacuum arc plasma by magnetic ducts. the underlying physics of MPI, and present some examples of MPI applications.