QRcodes are a popular type of two-dimensional barcode. They are also known as hardlinks or physical world hyperlinks. QRCodes store up to 4,296 alphanumeric characters of arbitrary text. This text can be anything, for example URL, contact information, a telephone number, even a poem! QRcodes can be read by an optical device with the appropriate software. Such devices range from dedicated QRcode readers to mobile phones.