U.S. Citizenship is obtained either by birth or naturalization. Naturalization refers to gaining U.S. citizenship after birth either through U.S. citizen parents, known as “derived” or “acquired” citizenship, or by applying for naturalization after meeting certain requirements. Generally, lawful permanent residents (LPRs or green card holders) age 18 or older who meet all eligibility requirements may file for naturalization.
Most naturalization applicants are required to take a test on English, and U.S. history and government.