QR codes (Quick Response codes) work by storing information in a two-dimensional barcode format that can be scanned by smartphones and dedicated readers. When scanned, the QR code translates the encoded information, which can include URLs, contact details, or product information, into a readable format. They are widely used for various purposes including marketing, payment processing, and event ticketing due to their ability to provide quick access to digital content without typing. Their popularity stems from their efficiency and versatility.