Bar Code, series of parallel vertical lines, or bars, used to assign a unique identification code to an item. In a bar code, a number or character is represented in binary form by a short sequence of alternating black and white bars of varying width. A bar code combines several of these sequences to create a unique set of numbers or characters that identifies the item. Laser scanners read the bar codes, and the information is then transmitted to a computer for processing. The most common use of the bar code identification system is to track inventory automatically. Bar codes are widely used for this purpose in supermarkets, warehouses, libraries, and retail stores.
Bar codes are printed on the product packaging itself or on labels and tags that are later affixed to the product. Bar code scanners use a laser beam of a specific frequency to distinguish the edges within the bar code. They can scan the bar code in any direction. There are a number of types of scanners, including wands, hand held scanners, projection/vertical scanners, and built-in counter scanners. Wands, handheld scanners, and projection scanners are moved across the bar code. Built-in scanners, such as the ones at supermarket checkout counters, read the bar code as the product is moved across the scanner.
Supermarket and retail bar codes are part of the Uniform Product Code (UPC), which gives a unique numerical code to each type of food or grocery product. These codes generally specify the manufacturer and the type or make of product, which in turn are used to compute the price of the product at the cash register. EAN (European Article Number) and JAN (Japanese Article Number) are used on retail goods in Europe, Japan, and other countries. Bar codes found on retail books are part of the International Standard Book Number (ISBN) system, which uses codes to identify a book’s country of origin and price.
Bar coding was introduced in the 1970s and has become a part of most businesses that need automated tracking of large quantities or inventories of items. It is also used in retail sales, to make identification cards, and to track documents or packages. More recently, bar coding has been applied in research settings. One such use is by geneticists, scientists who study the genetic structure of plants and animals. They employ bar coding to keep track of genes and pieces of deoxyribonucleic acid (DNA) in database collections and gene banks.
Structure of a Bar Code:
Bar codes provide unique labels for a wide range of products, from groceries to magazines. A complex coding system relates the pattern of widths of the dark and light bars to the number they represent. The number of digits a bar code represents varies; the EAN bar code depicted here is widely used in Europe and represents 13-digit numbers. Bar code patterns can be “read” rapidly by a laser scanner. The number obtained can be used to retrieve such information about the product as its nature, type, and price. The number itself is printed below the bar code.
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