In China, the social security number (social security number) is usually the same as the citizen ID number, that is, the 18-digit resident ID number. This is a unique identification uniformly managed by the state and contains information such as date of birth, area code, etc. It is strictly prohibited for any individual or organization to illegally generate or use it fraudulently. The following is a description of the structure of the ID number (only for legal understanding)： --- ###**Rules for Chinese resident ID number (example)** 1. **The first 6 digits**: Administrative division code (e.g.: `110105'represents Chaoyang District, Beijing). 2. **Middle 8 digits**: Date of birth (for example: `19900101` means January 1, 1990). 3. **Last 4 digits**： -Sequence code (digits 15-17): The sequence number of persons born on the same day in the same area, odd male and even female. -Check code (18th digit): Calculated from the first 17 digits (for example, 'x'represents the number 10). **Example**: `110105199001011234` (fictitious, only for format demonstration) --- ###**Examples of social security numbers from other countries (subject to local laws)** 1. **U.S. SSN (social Security number)** -Format: 'AAA-GG-SSSS` (such as `123-45-6789`). -Rules: The first 3 digits are the area code, the middle 2 digits are the group number, and the last 4 digits are the sequence code. 2. **British NINO (National Insurance number)** -Format: 'AB123456C` (combination of letters + numbers). --- ###**Important reminder** -**Legal purpose**: The social security number is only used in formal situations such as social security and taxation authorized by the government. -**Legal risks**: Forgery or misappropriation of other people's numbers is illegal and may face criminal liability. -**Privacy protection**: Do not disclose or share your real number, and beware of identity theft. If you need to handle social security business, please consult through official channels (such as the Social Security Bureau and the Government Service Network).