Diamond-Like Carbon (DLC) is a metastable form of amorphous carbon containing a significant fraction of sp3 bonds. It can have high mechanical hardness, chemical inertness, optical  transparency, smooth surface and low friction behavior.

Since their initial discovery in the early 1950s, DLC films have emerged as one of the most valuable engineering materials for various industrial applications, including microelectronics, optics, manufacturing, transportation, and biomedical fields. In fact, during the last two decades or so, DLC films have found uses in everyday devices ranging from razor blades to magnetic storage media.

Instead of using the term DLC, the term amorphous carbon is favored, to avoid the mix-up with diamond coatings, which are by definition crystalline.
These amorphous carbon coatings are classified into seven categories:

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• a-C	hydrogen-free amorphous carbon
  ta-C	tetrahedral-bonded hydrogen-free amorphous carbon
  a-C:Me	metal-doped hydrogen-free amorphous carbon (Me= W, Ti)
  a-C:H	hydrogen-containing amorphous carbon
  ta-C:H	tetrahedral-bonded hydrogen-containing amorphous carbon
  a-C:H:Me	metal-doped hydrogen-containing amorphous carbon (Me=W, Ti)
  a-C:H:X	modified hydrogen-containing amorphous carbon (X=Si,O,N,F,B)