FAFSA
Who
Every US citizen or eligible non-citizen, regardless of income.
What
Free Application for Federal Student Aid. The one form that unlocks federal grants, federal student loans, and most state and school aid. Some states require it for state scholarships even if you won't take loans.
Catch
Submit early. Many state and school programs award on a first-come basis once the FAFSA window opens (October for the following academic year).