The PIN number is not necessary to complete the FAFSA, but it's helpful. It is actually used to digitally sign off on your FAFSA, which verifies that all of your application information is correct. To get a PIN number, you actually have to apply for it here: http://www.pin.ed.gov/PINWebApp/appinstr.jsp. It generally takes 1-2 weeks for FAFSA to get back to you with a PIN. However, you do not have to wait for your PIN to start your application. Your PIN will be necessary to sign off and officially submit your application. For those who choose not to sign via PIN or forget to apply for one, you will be instructed to mail off a signed for that becomes viewable once your application is submitted.