Hot Metal Typesetting
The continuous casting, or mechanical typesetting, of the Linotype and Monotype machines introduced at the end of the 19th century, made composing by hand redundant. Instead of each metal sort (an individual letter or symbol) being composited into words and lines of text by hand, an operator could select, use and replace the sorts via a keyboard. The two systems, Monotype and Linotype, differed in that the Monotype system produced individual sorts while the Linotype system produced slugs that usually comprised a whole line of text. The Monotype system was popular for book production while the Linotype system was popular for newspaper publishing.