A Linotype machine is a line casting machine used in printing. The machine revolutionized printing and especially newspaper publishing, making it possible for a relatively small number of operators to set type for many pages on a daily basis. The Linotype machine operator enters text on a 90-character keyboard. The machine assembles matrices, which are molds for the letter forms, into a line. The assembled line is then cast as a single piece, called a slug, of type metal in a process known as hot metal typesetting. The matrices are then returned to the type magazine from which they came. The name of the machine comes from the fact that it produces an entire line of metal type at once, hence a line-o-type. This allows much faster typesetting and composition than original hand composition in which operators place down one pre cast metal letter, punctuation mark or space at a time.