Free Application for Federal Student Aid (FAFSA) is the preliminary requirement for students who wish to receive federal, state, or institutional financial aid. The information collected by the FAFSA application determines what grants, loans and work study a student may be eligible for in order to attend college. Only United States citizens and eligible non-citizens are permitted to file a FAFSA.
What information do you need to complete a FAFSA?
Which non-citizens are eligible to complete FAFSA?
Look here.
Both students and parents must create a studentaid.gov account and use it to complete the FAFSA. Parent immigration status does not impact a student's ability to receive aid.
CSS Profile is an additional financial aid applicaton required by many colleges and universities and is administered through College Board. You can find the list of colleges that require a CSS Profile
here.