The barcode of the book is the international standard book number of this book, which is called ISBN for short, with *** 13 digits. In addition to the bar code, the ISBN number of the book is also printed on the back cover of the book, which is the same as the bar code number, but the arrangement is different. * * * is divided into five groups of numbers, and each group of numbers is separated by a "-". The first set of numbers is 978 or 979, which is a special prefix code given to books by ean international. The second group is called group number, which is divided according to different countries and language families. In China, the number is 7. The third group is the publishing house code, which consists of 2-6 digits. The rule is that the bigger the publishing house, the fewer the digits. The fourth group is the book code, which is the 6 -2 digits of the books published by the publishing house. The last set of numbers has only one number, which is called the check code. It is calculated from the front 12 bit according to a certain calculation formula, and is used to verify whether the scanning result is correct when the scanner scans.