What is QR Code (ref wiki)
QR code (abbreviated from Quick Response Code) is the trademark for a type of matrix barcode first designed for the automotive industry in Japan.
A barcode is an optically machine-readable label that is attached to an item and that records information related to that item.
The information encoded by a QR code may be made up of four standardized types ("modes") of data (numeric, alphanumeric, byte/binary, Kanji) or, through supported extensions, virtually any type of data.
A QR code consists of black modules (square dots) arranged in a square grid on a white background, which can be read by an imaging device (such as a camera) and processed using Reed–Solomon error correction until the image can be appropriately interpreted; data is then extracted from patterns present in both horizontal and vertical components of the image.