An output device that creates characters and graphics by firing a stream of ink drops at a surface from one or more banks of tiny nozzles. The rapid displacement required to eject the drops from the nozzles may be achieved by surface boiling of the ink using tiny electric heating elements behind each nozzle, or by mechanical pressure using piezoelectric crystals behind the nozzles. The technology has developed to the extent that such printers can (on suitable media) offer comparable resolution and quality to the laser printer but at a much lower cost. Inkjet technology is also suitable for colour printing, nozzles being fed with three or four different colour inks (see CMY colour model, CMYK colour model). Inkjet printers can also act as plotters.

Considerable advances have been made in recent years and some inkjet printers can produce prints of photographic quality, though there are still concerns about the long-term stability of the dyes used.