How do QR codes differ from barcodes?
Barcodes come in all shapes and sizes. The first successful barcode was the Universal Product Code (UPC), used for tracking products in stores, which encodes 12 numbers. Other barcodes hold more information, for example the Royal Mail Mailmark (TM) type L barcode – which encodes 26 characters including ID, postcode and delivery point. QR codes are another kind of barcode, and there are many sizes. A version 4 QR code is 33 x 33 pixels in size and encodes up to 50 characters. A version 40 QR code is 177 x 177 and stores 2,953 bytes, or up to 7,089 digits. This particular QR code is so densely packed it looks like a picture of a snowstorm, and is rarely used because it’s difficult to scan successfully.