QR codes are a type of matrix barcode that can be read by smartphones and dedicated scanners. They were created in 1994 by Denso-Wave to allow for high-speed decoding. QR codes can store text, URLs, or other data. While initially popular in Japan and South Korea, their use is growing again with more smartphones able to read them through camera apps. QR codes see widespread use in marketing to provide web links and other information to customers.