A machine that revolutionized publishing almost as much as Gutenberg's invention of the moveable type. It was developed by German immigrant (to the USA) Ottmar Mergenthaler in the 1880s, based on a design by Charles T. Moore.

The machine made the process of typesetting about 5 times faster and was called the eighth wonder of the world by Thomas Edison. It allowed a typesetter to set type using a keyboard, one line at a time. Each keypress caused a so-called matrix, a small piece of metal imprinted with the correspondig character to be appended to the current line. When the line was completed, another key caused the assembled line to be transported to another part of the machine where it was used as a mold to cast the line with molten metal. Afterwards, the matrices were automatically returned to the correct place in the magazine.

It is easy to see how this machine revolutionized printing, since the typesetting previously had to be done by hand, one character at a time. Of course this meant that most of the hand compositors lost their jobs as the Linotype spread. However, it made printed text much cheaper; prior to the Linotype, newspapers seldom had more than a few pages, and not everyone could afford books.

Mechanical typesetting machines that worked the same way as the Linotype were the standard in typesetting well into the second half of the 20th century, until the advances in semiconductor technology made DTP software viable. Even before the printing process became fully digital, hybrid methods came into use, where unformatted text was fed into a computer, which optimized line lengths and justification and produced a punched tape which controlled Linotype-like machines.