The I-797 is a 'Notice of Action' issued by USCIS. It is used on a variety of occasions:
- to show a petition has been received at the Chicago Lockbox/Missouri Service Center or one of the four individual service centers,
- to show petition has been adjudicated either from the service center and/or through interview,
- to show approval for an alien to acquire a visa, to remain in the US or to change status within the US.