What's the difference between a social security number and an ITIN? I know an ITIN always begins with the # 9.

Answer 1

An ITIN is an Individual Taxpayer Identification Number. It's issued to someone who needs to report US based income but is not entitled to an SSN. It has nothing to do with Homeland Security as another poster claims. ITINs were around long before HS was ever conceived.

Answer 2

After all the clarifications: Currently you are on an H4 visa as a dependent of an H1B visa holder. You will be so until you do get your greencard or until you turn 21, whatever comes first. Until you get your greencard you cannot get instate tuition. Visa holders are neither eligible for instate tuition nor financial aid. Yes, I know your parents pay taxes, but that's the rules nevertheless. You can try changing the system once you are an US citizen, currently you are a guest. As a guest you play by the rules of your host. If you don't like the rules you can also leave if you don't like the rules (admittedly without your parents only after you turned 18). While you are pretty well informed for a 16 year old (I think it is excellent that you at least inform yourself about the subject) you are not in an unique or strange situation. Many people who get a greencard through work sponsorship and fall into one of the categories where there are wait times are in the same situation. I have some friends who also need to wait until they can file an I-485. So no, you are not unique, and you are not exceptionally disadvantaged.

Answer 3

itin is a tax payer identification number.
this is a number given to people that cannot apply for ssn. (don't qualify) the ITIN will allow you to claim taxes, open bank accounts and establish credit. this was created by the home land security to allow foreigners to invest in the united states.