Printer helps in taking out hard copy of a document stored in electronic form so that you can preserve it in a permanent readable text form. Earlier versions of printers were attached to the computer with printer cable, and in most of the new printers USB cable is attached to a computer. Now some computers are equipped with built-in wireless/ Ethernet technology. Usually individual printers are compatible to both local and network connections at the same time. Some advance printers can be directly used with memory sticks, memory cards, digital cameras, scanners while some other printers have scanners and fax machines combined in a single unit, besides functioning as photocopiers.
The earlier versions of printers, such as Impact and Pen-based plotters have now either become obsolete or are used in some very special applications only. In Impact printers like Typewriter-derived printers, Daisy wheel printers, and Teletypewriter-derived printers, the ink is pressed forcibly on the paper similar to action of typewriter. There are predetermined characters in such printers and mostly these were monochrome printers that can be used in a single typeface at a time, and for bolding and underlining over-striking is done. Dot Matrix printers are still used as a low cost alternative in various homes and businesses. There was a time when Pen based plotters were often used in engineering and architectural works. There were mechanically run pens to create text and images.
Today printing technology has taken a quantum leap and most modern printers are now available that can be used for various purposes, like printing, faxing, photocopying etc. The modern print machines usually function with following technologies:
(1) Toner based
(2) Liquid Inkjet
(3) Solid Ink
(4) Dye sublimation
Laser/LED printer are the toner based printers that causes the toner adhesion to the print drum. This type of printers has disadvantage that besides causing pollution similar to cigarettes it emits ultrafine particles that are potentially harmful for health especially respiration. Liquid inkjet printers are mostly preferred by general consumers.