Optical disc
Discs in large quantities can either be replicated or duplicated. In replication, the process explained above is used to make the discs, while in duplication, CD-R, DVD-R or BD-R discs are recorded and finalized to prevent further recording and allow for wider compatibility. (See Optical disc authoring). The equipment is also different: replication is carried out by fully automated purpose-built machinery whose cost is in the hundreds of thousands of US dollars in the used market, while duplication can be automated (using what's known as an autoloader) or be done by hand, and only requires a small tabletop duplicator.