Linotype machine
The Monotype machine worked by casting letters from "hot metal" (molten metal) as pieces of type. Thus spelling mistakes could be corrected by adding or removing individual letters. This was particularly useful for "quality" printing - such as books. In contrast, the Linotype machine—a direct competitor—formed a complete line of type in one bar. Editing these required replacing an entire line (and if the replacement ran onto another line, the rest of the paragraph). But Linotype slugs were easier to handle if moving a complete section of text around a page. This was more useful for "quick" printing - such as newspapers.