A QR code is a square pattern of black and white blocks that stores information, which can be read instantly by a smartphone camera or scanner. The letters QR stand for “quick response,” because scanning one takes you immediately to a website, video, menu, or other digital content.

You've probably seen QR codes on restaurant tables (to view menus), museum exhibits (to learn more about displays), or product packaging. The Japanese company Denso Wave invented QR codes in 1994 to track car parts in factories, but they became popular worldwide because smartphones made them easy for everyone to use.

QR codes work like sophisticated barcodes, but they can hold much more information: up to several thousand characters, compared to a barcode's 20 or so. The three square corners help your phone recognize and orient the code correctly, even if it's tilted or partially dirty.

During the COVID-19 pandemic, QR codes became ubiquitous as restaurants and businesses used them to share information without physical contact. Today they appear everywhere: on concert tickets, business cards, food labels, and even gravestones, where they can link to memorial pages. Some creative uses include QR codes in crossword puzzles, on buildings, and even in agricultural fields visible from airplanes.