In the United States, a Social Security number (SSN) is a nine-digit number issued to U.S. citizens, permanent residents, and temporary (working) residents.
A Social Security Number (SSN) consists of nine digits, commonly written as three fields separated by hyphens: AAA-GG-SSSS. The first three-digit field is called the "area number". The central, two-digit field is called the "group number". The final, four-digit field is called the "serial number".