The process of mass-producing compact discs and other forms of optical disc. The process of replication, like the earlier means of pressing vinyl records, involves the use of a relief template, in the case of optical discs, that is a glass master. This master has been encoded (using data from the master tape) with a series of pits and lands, which corespond to the pits and lands to ultimately be stamped on the disc. These pits and lands are stamped into a metal plate, called a stamper, which thus contains a "negative" of the pit/land pattern. The stamper then stamps one side of the disc, under high pressure and temperature. Then, the stamped side is covered with a thin layer of aluminum, so as to create a reflective layer. A protective coating is then applied, and a label is added to the reverse side. The final step involves punching the center hole (by which the disc is accurately held in the reader or drive). See Compact Disc.