Bar codes are patterns used to encode and compare information. Using parallel lines and spaces are represented by symbols that special readers provided data. The operation of these codes are based on coding conventions, called symbologies. Bar codes became commonplace in the decade of the seventies and now are common in commercial transactions, since they are very useful for identifying products and their characteristics. For example, use these codes to quickly find information on prices and other items purchased by the public at retail outlets.
The cashiers of supermarkets examined under a scanning bar codes printed on each of the products purchased by a customer. Prices are entered by these codes at the checkout.