A QR code (short for 'Quick Response code') is a two-dimensional barcode that stores information—like URLs, text, or contact details—in a square grid of black and white modules. The term 二维码 literally breaks down as 二 (èr, 'two') + 维 (wéi, 'dimensional') + 码 (mǎ, 'code' or 'symbol'). Unlike traditional barcodes, which are one-dimensional and store data only horizontally, QR codes encode information both horizontally and vertically, allowing much greater data capacity and faster scanning.

This technology is ubiquitous in daily life across China: used for mobile payments (e.g., WeChat Pay or Alipay), event ticketing, sharing business cards, accessing Wi-Fi networks, and even ordering food at restaurants. Most smartphones can scan QR codes directly using their built-in camera app without needing a separate scanner.