Design and layout of the printed word.
Typography began with the invention of
writing and developed as printing spread
throughout Europe following the invention of
metal moveable type by Johann Gutenberg about
1440. Hundreds of variations have followed
since, but the basic design of the Frenchman
Nicholas Jensen (c. 1420-80), with a few
modifications, is still the ordinary
(`roman') type used in printing. Type sizes
are measured in points (there are
approximately 2.8 points to the millimetre);
the length of a typeset line, called the
measure, is measured in pica ems (1 pica em
has a width of a little over 4 mm/0.15 in).
The space between lines (known as leading) is
also measured in points, although new
photosetting and computer-assisted setting
systems also work in metric sizes.