There are a number of variants of QR code, each with differing characteristics in terms of readability, data density and error correction. Currently the variant offering the greatest data capacity is “40L” (type 40, error correction level L). This utilises a 177 x 177 dot matrix and can be used to represent up to 4,296 alphanumeric characters or 7,089 numeric-only characters.
The term QR Code is an abbreviation of “Quick Response Code” and is the trademark of a type of two-dimensional barcode (also known as “matrix” barcode). It was invented in 1994, initially for use within the Japanese motor industry but is now widely used for a variety of applications such as marketing and inventory management.