The X in the ID card belongs to the digital verification code. The ID card number is compiled according to the national standard and consists of 18 digits: the first six digits are the administrative division code, the seventh to fourteenth digits are the date of birth code, the 15th to 17th digits are the sequence code, and the 18th digit is the verification code.
The check code is calculated by the number preparation unit according to the unified formula. If a person's tail number is 0-9, there will be no X, but if the tail number is 10, then it must be replaced by X, because if 10 is used as the tail number, the person's ID card will become 19 digits, and the 19 digit number violates the national standard, And China's computer application system does not recognize 19 ID number. X is the Roman numeral 10. Replacing 10 with X can ensure that citizens' ID cards meet national standards.
The resident identity card of the people's Republic of China is referred to as "identity card". On April 6, 1984, the State Council issued the trial regulations of the people's Republic of China on resident identity cards, and began to issue the first generation of resident identity cards.
Since March 29, 2004, the Chinese mainland has officially launched the second generation of resident identity cards for the resident non-contact IC card smart chips. The two generation ID cards are on the surface of the ID card and the printing anti-counterfeiting technology, using personal color photographs, and can read the information in the digital chip by machine.