What is Social Security?

Social Security (also know as FICA- Federal Insurance Contributions Act) and Medicare are U.S. government programs that provide benefits for U.S. citizens and U.S permanent residents, usually for retirement. It is financed by taxes withheld from the paychecks of working people. F-1 or J-1 students and scholars who are "non-residents for tax purposes" are not required to pay these taxes. See the IRS Publication 519, to determine if you are 
considered a resident or non-resident for tax purposes.