The Monotype system is a system for printing by hot-metal typesetting from a keyboard. The two most significant differences from the competing Linotype machine are thatit is divided into two machines, the Monotype keyboard and the Monotype caster, which communicate by perforated paper tape. It is not necessary to have the same number of each machine. the Monotype caster casts individual letters, which are assembled into lines in a fashion similar to classical movable type. This requires a more complex high-speed water-cooled casting mold, but only requires one matrix per possible character.