Two-dimensional barcode (dimensional barcode), also known as two-dimensional bar code, is a readable bar code expanded on the basis of one-dimensional bar code. The device scans the 2D barcode and obtains the information contained in it by identifying the binary data recorded in the length and width of the barcode. Compared with one-dimensional barcodes, two-dimensional codes record more complex data, such as pictures, network links, etc.

Two-dimensional barcodes/dimensional barcodes use certain geometric figures according to certain rules. Black and white graphics distributed on a plane (two-dimensional direction) record data symbol information; in coding, the concepts of "0" and "1" bit streams that form the basis of the computer's internal logic are cleverly used, using several binary Corresponding geometric shapes represent text numerical information, which is automatically read through image input equipment or photoelectric scanning equipment to achieve automatic information processing: it has some unique features of barcode technology: each code system has its own specific character set. ;Each character occupies a certain width; has certain verification functions, etc. At the same time, it also has the features of automatically identifying different lines of information and processing graphics rotation changes. Among many types of two-dimensional barcodes, commonly used code systems include: Data Matrix, Maxi Code, Aztec, QR Code, Vericode, PDF417, Ultracode, Code 49, Code 16K, etc. The QR code was developed by the Japanese company Denso-Wave in 1994. invention. QR comes from the abbreviation of "Quick Response" in English, which means quick response. It comes from the inventor's hope that the content of the QR code can be decoded quickly. QR codes are most common in Japan and South Korea; they are currently the most popular two-dimensional barcode in Japan.