Postal code generally consists of six digits, the first two digits represent provinces, autonomous regions or municipalities directly under the central government, the middle four digits represent postal code, and the last digit is the check code.

The invention and use of postal codes can be traced back to the end of 19, originally for the convenience of sorting and delivering mail by the US Postal Service. Later, postal codes were gradually applied around the world and became an important symbol of mail and express delivery. In addition to postal codes, there are many other ways to locate and identify addresses, such as GPS positioning and QR code, which are convenient for people's life and business activities.