What Is a QR Code?
A QR code (Quick Response code) is a two-dimensional barcode made of a grid of black and white squares that stores data — usually a URL, but also text, contact details or Wi-Fi credentials — and can be read instantly by any smartphone camera.
QR codes were invented in 1994 by Masahiro Hara, an engineer at the Japanese company Denso Wave, to track automotive parts faster than the 1D barcodes of the time allowed. Because the pattern is two-dimensional rather than a single row of lines, a QR code can hold vastly more information in the same physical space.
Reading one requires no special hardware — any modern phone's default camera app recognizes and decodes a QR code automatically, which is the main reason they went from an industrial tool to a consumer-facing one. Scanning triggers whatever the code was built to do: open a link, save a contact, or display plain text.