A QR code is a two-dimensional square code made up of black and white fields. Characteristic of QR codes are the special markings in three of the four corners. QR is short for 'quick response'.
Using a QR code, it is possible to encode a considerable amount of information in a limited space. Depending on the quantity of information to be conveyed, machine-readable 2D codes can be created with dimensions that are less than 5 x 5 mm. Error correction is also possible, so that even if 25% of a QR code has been obliterated, it can still be read.