Well you've submitted your petition or application and you are waiting for the USCIS to rule on your case.  Before they rule though you are likely to receive a notice to appear at an Application Support Center (ASC) for Biometrics Collection.  So just what Biometrics are collected.  The answer varies because the use varies.  In some cases they just need a print of your index finger so they can print it on your card.  In other cases they need to do a complete background investigation and they will need more data.  To tell the ASC what data they need the USCIS places a code in the upper right corner of the ASC notice.  Here is what those codes mean:

 1 – 10 Prints Only - They will take a scan of your fingerpints.

2 – Photo, Signature, Index Finger Print - They will take a digital photo, obtain your signature and finger print your index finger.

3 – 10 Prints, photo, signature, and Index Finger Print - All of the above.  If it can be done they will do it.