What Is USCIS?

U.S. Citizenship and Immigration Services (USCIS) is the federal agency that oversees lawful immigration to the United States.
USCIS is responsible for processing applications and petitions for:

Green cards

Citizenship

Work permits

Family immigration

Humanitarian programs

Immigration benefits and documentation

They do not issue visas abroad (that is the U.S. Department of State), but they process most petitions inside the United States.

Forms for the U.S. citizen sponsor

• Form I-130, Petition for Alien Relative: This is the initial petition to establish the relationship for immigration purposes.
• Form I-864, Affidavit of Support: This form proves that the sponsor has sufficient income to support the immigrant spouse. 

Forms for the immigrant spouse

• Form I-485, Application to Register Permanent Residence or Adjust Status: Filed if the spouse is already in the U.S. and wants to adjust their status to a green card holder without leaving the country.
• Form I-130A, Supplemental Information for Spouse Beneficiary: Provides additional information about the spouse.
• Form DS-260, Immigrant Visa Electronic Application: Filed for the consular processing route, when the spouse is living abroad.
• Form I-693, Report of Medical Examination and Vaccination Record: The immigrant spouse must complete a medical exam with a USCIS-approved civil surgeon.
• Form I-765, Application for Employment Authorization: Can be filed to apply for a work permit while waiting for the green card to be processed.
• Form I-131, Application for Travel Document: Can be filed for "Advance Parole" to allow travel outside the U.S. while the adjustment of status application is pending. 
• Form I-751 , Petition to Remove Conditions on Residence: Filed jointly (or with a waiver) by conditional residents (CR-1/CR-2) to remove the 2-year green card conditions.
• Form I-90,  Application to Replace Permanent Resident Card: Used for renewing or replacing a lost, stolen, or expired green card.

Required documents

• Civil documents: Birth certificates, marriage certificate, divorce decrees or death certificates for any prior marriages.
• Financial documents: Tax returns and other financial evidence to support the Affidavit of Support.
• Passport-style photographs: Required for both the sponsor and the immigrant spouse.
• Police certificates: May be required from countries where the spouse has lived. 
• Proof of bonified marriage : Joint memberships and activities, life events such as wedding photos, children together, Affidavits From Friends & Family, Communication Records, Photos Together, travel and visit, financial support.