Diamond-like carbon (DLC) is a unique material that possesses superb physical and chemical properties. However, there are several synonyms for the term DLC. One of the most commonly used phrases is amorphous carbon, which describes a disordered and non-crystalline form of carbon. Another synonym for DLC is tetrahedral amorphous carbon (ta-C), which refers to a specific type of amorphous carbon that has a tetrahedral arrangement of atoms. Another term for DLC is hydrogen-free amorphous carbon (a-C), which distinguishes it from hydrogenated DLC. Finally, some researchers refer to DLC as hard carbon, as the material is extraordinarily hard and scratch-resistant.