A social security number is a primary means of identification through the federal government. Any type of interaction with them will generally require that you know your social security number in order for them to process your information. It is the requirement of every United States citizen to have a social security number by the time they reach adulthood for this very reason.
Apply For SS Card
Anyone that is a citizen of the United States is eligible to apply for a social security card. For most people this is done by their parents shortly after they are born. Unfortunately, not all parents realize just how important this document is and do not take this step. If you do not have a replace social security card online and are a citizen of the United States you will want to apply for one as soon as possible so that you have it for when you will almost definitely need it.
Other than citizens the only people that are eligible for a social security number are those that are legally allowed to work in the United States. This approval has to be given by the Department of Homeland Security before you can apply for one. This is typically done before you ever even enter the country. If you do have approval to work and have not yet applied you should do so as soon as possible as you will need it to file your taxes at the end of the year, which is required by law.
There really are no other circumstances that make someone eligible for a social security number. This can make it very difficult for those that have come to the country illegally as they are not able to gain legal employment, get government benefits and a host of other issues. It is a common misconception that illegals are able to do these things, which is something that is suspected to lead to them coming to this country. Unfortunately, they often find that they have to take employment for very low wages from business that are willing to operate in an illegal fashion.
If you are eligible for a social security card it is best to apply for one as soon as you realize that you can. This can be done easily online or in person at the office closest to you. You will simply need to prove your citizenship or approval to work in this country. They will then submit your application and the actual card will be mailed to your home address within 2 weeks of the application. Be sure that you take care of this as soon as possible.
In short, there really are only two circumstances that make you able to get this type of federal identification. You either need to be a citizen of the country or have approval to work here. If you do not have one of these two qualifications you will not be legally allowed to obtain a social security number.