The shared code is a two-dimensional code, also called a two-dimensional bar code. The common QR code is QR code, which means quick response. It is a very popular coding method on mobile devices in recent years. Compared with the traditional bar code, it can store more information and represent more data types. 2-dimensional bar code is a kind of black-and-white figure which is distributed on a plane (two-dimensional direction) according to certain rules and records data symbol information. 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 function of automatically identifying different line information and processing graphics rotation change points.