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Barcodes consisting of black lines with spaces between them are often used to keep track of inventory and simplify other aspects of running certain businesses, especially grocery stores and other places where complex tracking is necessary. A barcode reader provides a quick way to translate the codes, and using one requires very little effort on the part of workers. Barcodes represent numbers that can be linked to items in a database, and the readers have an ability to measure light reflections, allowing them to pick up the barcodes off the surfaces of packaging. Most barcode readers are shaped either like a gun or a pen, but some are set up in fixed positions.
Prior to the invention of barcodes and the barcode reader, grocery stores and other kinds of shops had much more difficulty keeping track of inventory, relying more heavily on manual methods. Knowing exactly how many items are available in a store is often crucial for retailers because it allows them to keep a tally of how well things are selling and simplifies the process of making decisions about quantity when making another order. Typically, a barcode reader is set up at each cash register, connected to a computerized database with information on all the items in the store. When the clerk scans items during a purchase, the system registers the sold item in the database, keeping a real-time inventory estimate.
Barcodes are always made up of black lines because of the way readers work. Since black surfaces are typically known to absorb more light and brighter surfaces are more reflective, bouncing light off a barcode generates a simple pattern of spaces and lines that can be registered with relatively simple equipment. The actual technology used in barcode readers has changed over time, including the use of lasers, light emitting diodes (LEDs), and even actual cameras with the ability to pick up codes from a greater distance or read multiple codes simultaneously.
The form factor for a barcode reader is often dependent on its use. Many are designed so that clerks and other operators can maneuver them for easier access to barcodes, and these are often shaped a lot like guns or pens. Others are set up so that they remain stationary and the barcode is moved into a position where the scanner can read it, including the kind that are set up inside the conveyer belt tables in some grocery stores.