QR Code (abbreviated from Quick Response Code) is the trademark for a type of matrix barcode (or two-dimensional code) first designed for the automotive industry. More recently, the system has become popular outside the industry due to its fast readability and large storage capacity compared to standard UPC barcodes. The code consists of black modules (square dots) arranged in a square pattern on a white background. The information encoded can be made up of four standardized kinds ("modes") of data (numeric, alphanumeric, byte/binary, Kanji), or through supported extensions, virtually any kind of data.
The QR Code was invented in Japan by the Toyota subsidiary Denso Wave in 1994 to track vehicles during the manufacturing process, and was originally designed to allow components to be scanned at high speed. It has since become one of the most popular types of two-dimensional barcodes.
Source: QR Codes on Freebase, licensed under CC-BY