The general principle of typesetting remains the same: the composition of glyphs into lines to form body matter, headings, captions and other pieces of text to make up a page image, and the printing or transfer of the page image onto paper and other media. The two disciplines are closely related. For example, in letterpress printing, ink spreads under the pressure of the press, and typesetters take this dynamic factor into account to achieve clean and legible results.

Letterpress era

The diagram at right illustrates a cast metal sort: a face, b body or shank, c point size, 1 shoulder, 2 nick, 3 groove, 4 foot. Wooden printing sorts were in use for centuries in combination with metal type.

Copies of formes were cast when anticipating subsequent printings of a text, freeing the costly type for other work. In this process, called stereotyping, the entire forme is pressed into a fine matrix such as plaster of Paris or papier-mache to create a negative, from which the stereotype forme was cast of alloy.

Hand compositing was rendered obsolete by continuous casting or hot-metal typesetting machines such as the Linotype machine and Monotype at the end of the 19th century. The Linotype, invented by Ottmar Mergenthaler, enabled one machine operator to do the work of ten hand compositors. Hand-compositing and letterpress printing did not fall completely out of use, and has undergone a revival since the introduction of digital typesetting. However, it is a very small niche within the larger typesetting market.

Phototypesetting

Phototypesetting systems first appeared in the early 1960s and rapidly displaced continuous casting machines. These devices consisted of glass disks (one per font) that spun in front of a light source which selectively exposed characters onto light-sensitive paper. Originally they were driven by pre-punched paper tapes. Later they were hooked up to computer front ends.

One of the earliest electronic photocomposition systems was introduced by Fairchild Semiconductor. The typesetter typed a line of text on a Fairchild keyboard that had no display. To verify correct content of the line it was typed a second time. If the two lines were identical a bell rang and the machine produced a punched paper tape corresponding to the text. With the completion of a block of lines the typesetter fed the corresponding paper tapes into a phototypesetting device which mechanically set type outlines printed on glass sheets into place for exposure onto a negative film. The film was then cut-and-pasted into full page galleys used to create plates for offset printing.

Digital era

Computers excel at automatically typesetting documents. Character-by-character computer-aided phototypesetting was in turn rapidly rendered obsolete in the 1980s by fully digital systems employing a raster image processor to render an entire page to a single high-resolution digital image, now known as imagesetting.