Learn in the textbookInput Devices for Capturing Text and Images
DefinitionA barcode reader (バーコードリーダー) is an input device that shines light on a barcode, which encodes digits and other characters as lines of varying width and spacing, and reads them from the differences in reflection.
ExplanationWhat it reads is a number that identifies a product or item, and the computer uses that number to look up the name and price in its own records. Barcode readers are used for checkout at shop registers and for logging goods in and out of warehouses.
AnalogyThink of the number label on the spine of a library book, read not by eye but with a single quick sweep of light.
Memory hookBar as in a stick: the widths of the sticks and the gaps between them are themselves a code for the digits.