A bar code is a pattern of lines and spaces of varying widths that represents a product in a machine-readable format. It is printed on a variety of items – from products in stores to blood bags and food cartons – and organizations use it to track and keep inventory, record data, communicate information and perform other tasks.

In retail settings, a bar code is often used by cashiers to scan items as customers buy them so that receipts can be automatically generated and stored in the store computer system for inventory tracking and sales management. Supermarkets and other retailers are the largest users of bar codes, but they are also used by manufacturers, blood banks, hospitals and many other kinds of organizations.

There are several types of bar codes, known as symbologies, each with its own unique characteristics. The choice of a particular type depends on several factors, including the data it encodes, the environment in which the code will be used, the size of the characters, and the scanning and printing processes that are most convenient or economical. The most widely used type of bar code is the Universal Product Code (UPC), which has 26 characters for identification purposes and is supported by virtually all scanners and computer systems. Another common barcode is the GS1-128 barcode, which has 43 characters and works well with most software and hardware devices, including smartphones, tablets, and computers.

Barcodes offer a number of advantages over other forms of automatic identification and data capture. In addition to being far more accurate than manually-entered data, they also save time by allowing employees to simply scan an item and transmit the information directly to the appropriate database. This greatly reduces the need for manual data entry, which can be error-prone and slow.

As a result, businesses using barcodes can count and process large quantities of items more quickly. In addition, the accuracy of barcodes provides a higher degree of inventory control and allows companies to better calculate the turnover of their stock, which can lead to less storage space required in the warehouse.

Another benefit is that the simplicity of barcode scanners makes it easy for any employee to learn to operate them, requiring very little training and supervision. In contrast, other AIDC technologies require more complex and costly systems of software and special-purpose equipment to function.

Barcodes are a crucial tool for many businesses, especially those that ship high volumes of merchandise. In the case of warehouses, bar code scanning enables employees to efficiently count products as they arrive in the facility, are picked and packed for shipment, and are shipped to customers. This eliminates human errors and ensures that all customer orders are accurately dispatched. Other business applications include job costing and tracking – when an employee moves from one work area to the next, they can scan their badge with a barcode reader to link the UID of that box to all relevant details in the database – and asset inventory control, where fixed assets are tagged and tracked so that payroll costs can be allocated appropriately.