Barcodes are comprised of a series of vertical lines of varying thicknesses and gaps. The numbers underneath the lines correspond to the product code, which is unique to every item sold. When a barcode is scanned, the number is transmitted to a computer which looks up further information about the product in a database.Barcodes were invented in the 1970s as a way to automate the process of inventory and product tracking, and have since become ubiquitous in retail stores, warehouses and other settings. The numbers on the barcode help identify the product and streamline the supply chain, making it easier to keep track of which products are selling and which need to be replenished. Furthermore, barcodes have helped reduce human errors in tasks such as pricing and manual inventory counts.