What  is a PIN?
A PIN is a Personal Identification Number.  Since you may be filling out your application online, you will not be able to provide a hand written signature verifying your information.  Therefore, the PIN will serve as an electronic method you can use to 'sign' and validate the information you provide. 

How do I get a PIN?
If you do not have a PIN, go to http://www.pin.ed.gov/ and select "Apply for a PIN." To apply for a PIN, you will need to provide your social security number, full name, complete address, date of birth, e-mail address (if you have one) and a security pass phrase.

Once you have completed the PIN application, select the "Submit Request" button. If the information you entered passed an identity check with the Social Security Administration, a PIN will be mailed or emailed to you in approximately three business days.

I lost my PIN.  What should I do?
If you have lost or forgotten your PIN, you will need to request that it be sent to you again.
Go to http://www.pin.ed.gov/  and select "Request a Duplicate PIN"