What is SSN? (Social Security Number)

SSN is the identification number of a United States citizen or temporary resident alien. This number is used to track and pay a person's social security data. SSN is required for a person to benefit from social security programs such as retirement, disability, and survivorship benefits. The SSN is also part of a person's tax roll and is used by various government and private companies for purposes such as verifying identity and applying for credit.