These use a series of small pins to strike a ribbon coated with ink, causing the ink to transfer to the paper at the point of impact.
Dot matrix printers use a stored energy system, with pins welded to a sun ring spring over a permanent magnetic pole which holds the pins against the spring. When a dot is required, the printer's CPU energises the magnet, neutralising its force and the pin is released to strike the inked ribbon, leaving a dot on the page. As the print head moves across the page, the pins are released to allow a pattern of dots laid down within an invisible matrix to form a character.
Character printers
These have a ball or series of bars with actual characters (letters and numbers) embossed on the surface. The appropriate character is struck against the ink ribbon, transferring the character's image to the paper. Character printers are fast and sharp for basic text, but very limited for other use.
