The Immigration and Nationality Act allows for the immigration of foreigners to the United States based on relationship to a U.S. citizen or legal permanent resident. Family-based immigration falls under two basic categories: unlimited and limited.

• Family First Preference (F1): Unmarried sons and daughters of U.S. citizens, and their children, if any. (23,400)
• Family Second Preference (F2): Spouses, minor children, and unmarried sons and daughters (over age 20) of lawful permanent residents. (114,200)
• At least seventy-seven percent of all visas available for this category will go to the spouses and children (F2A);
  the remainder will be allocated to unmarried sons and daughters (F2B).
• Family Third Preference (F3): Married sons and daughters of U.S. citizens, and their spouses and children. (23,400)
• Family Fourth Preference (F4): Brothers and sisters of United States citizens, and their spouses and children, provided the U.S. citizens are at least 21 years of age. (65,000)