What is a QR code? What is the use of the legendary QR code?

Two-dimensional code, also known as two-dimensional barcode, is a readable barcode based on one-dimensional barcode. The equipment scans the two-dimensional bar code, and the information contained in it can be obtained by identifying the binary data recorded on the length and width of the bar code. Compared with one-dimensional bar code, the data recorded by two-dimensional code is more complicated, such as pictures and network links.

Two-dimensional code/two-dimensional code is to record the information of data symbols distributed on a plane (two-dimensional direction) according to certain geometric figures and certain rules. In coding, the concepts of "0" and "1" bit streams, which constitute the internal logic foundation of the computer, are skillfully used, and several geometric figures corresponding to binary are used to represent the numerical information of characters, which can be automatically read by image input equipment or photoelectric scanning equipment to realize the automatic processing of information: it has some characteristics of barcode technology: each code system has its own specific character set; Each character occupies a certain width; It has certain verification function. At the same time, it also has the characteristics of automatically identifying different lines of information and dealing with the rotation and change of graphics. Among many kinds of two-dimensional codes, the commonly used coding systems are: data matrix, Maxicode, AZTEC, QR code, Vericode, PDF 4 17, Ultra code, Code 49, Code 16K, etc. Two-dimensional code was invented by Denso Wave Corporation of Japan in 1994. QR comes from the abbreviation of "Quick Response" in English, that is, the meaning of quick response, and comes from the inventor's hope that the QR code can quickly decode its content. QR codes are the most common in Japan and South Korea. It is the most popular two-dimensional space bar code in Japan.