United States citizens and Lawful Permanent Residents can petition and sponsor certain family members:

Immediate Relative Immigrant Petitions – available to people described as Immediate Relative of a United States citizen:

• Spouse;
• Unmarried children under 21 years of age;
• Adopted children; and
• Parents of a United States citizen who is at least 21 years old.

Family Preference Immigrant Petitions:

• Family First Preference (F1): available for unmarried sons and daughters (21 years or older) of United States citizens, and their minor children, if any;
• Family Second Preference (F2): available for spouses, minor children, and unmarried sons and daughters of Lawful Permanent Residents;
• Family Third Preference (F3): Married sons and daughters of U.S. citizens (any age), and their spouses and minor children.
• Family Fourth Preference (F4): Brothers and sisters of U.S. citizens, and their spouses and minor children, provided the American citizen is at least 21 years of age.