Barcodes can be printed on cards and tags to uniquely identify items and data using a series of black bars and white spaces. Common 1D barcodes include Code39, Code128, and EAN13, while 2D QR codes can also be printed and scanned by smartphones. Barcodes are widely used for managing inventory, membership systems, and product pricing when scanned by optical barcode readers in retail stores, warehouses, and on mobile devices. They provide benefits such as improved management, time and cost savings, and easy automatic identification of data.