Printers and scanners are arguably the most common accessory not including mouse, monitor and keyboard; most people are familiar with what a computer printer is. The first printers were known as "line printers" and were large enclosures that would take a full box of listing paper (11 inch wide, fanfold with sprocket holes up each side); the characters were on a fast revolving band inside the printer and as the character the machine needed to print came around, the printer would punch it forward through an inked ribbon and on to the paper. Desktop printer technology has come a very long way since these early days; the modern day ink jet or laser printer maintains very little in common with its predecessor.
A printer is used to produce hard copy output from a computer, a computer scanner is exactly the opposite, and it is used to get hard copy input into a computer system. They work in a similar fashion to a photocopier, using a high intensity light shone through the paper that the original hard copy is printed on to form a photographic like digital image. If the input is text based there may be some form of OCR (Optical Character Recognition) software forming a bridge between the scanner and the computer, to convert the scanned images into machine readable form.
A printer is used to produce hard copy output from a computer, a computer scanner is exactly the opposite, and it is used to get hard copy input into a computer system. They work in a similar fashion to a photocopier, using a high intensity light shone through the paper that the original hard copy is printed on to form a photographic like digital image. If the input is text based there may be some form of OCR (Optical Character Recognition) software forming a bridge between the scanner and the computer, to convert the scanned images into machine readable form.