QR code is square, common is black and white. In the three corners, there are smaller, square patterns like "back". These three are the patterns that help the decoder to locate the software. Users do not need to align. The data can be read correctly regardless of the angle.
The Japanese JIS X 0510 standard was issued in January 1999, and its corresponding ISO international standard ISO/IEC 18004 was approved in June 2000. According to Denso Wave's website data, the QR code is an open standard, and the specifications of the QR code are open. Although the patent rights held by Denso Wave, it will not be run.
In addition to the standard QR code, there is also a format called "Micro QR Code", which is a reduced version of the QR code standard and is mainly designed for applications that cannot handle larger scans. The micro QR code also has a variety of standards and can store up to 35 characters.