Impressio Librorum (Book Printing), plate 4 from the Nova Reperta (New Inventions of Modern Times), c. 1580–1605, engraving by Theodoor Galle after a drawing by Jan van der Straet, c. 1550; in the British Museum.
printing, Process for reproducing text and illustrations, traditionally by applying ink to paper under pressure but today including various other methods. In modern commercial printing, three basic techniques are used. Letterpress printing relies on mechanical pressure to transfer a raised inked image to the surface to be printed. Gravure printing transfers ink from recessed cells of varying depths. In offset printing the printing and nonprinting areas of the plate differ not in height but in wettability.
