Post Link : How to Generate Bar Code with PHP
A barcode is an optical, machine-readable, representation of data; the data usually describes something about the object that carries the barcode. Originally barcodes systematically represented data by varying the widths and spacings of parallel lines.
Barcodes were initially scanned by special optical scanners called barcode readers. Later application software became available for devices that could read images, such as smartphones with cameras.
Now a days barcodes are used by various e-commerce application that simplify the product inventory management. E-commerce sites like flipkart, amazon, snapdeal etc are using these barcode features and this barcode is available in their Invoice Bill.