A green card is an official document that allows a non-U.S. citizen to live and work permanently in the United States. It serves as proof of a person's lawful permanent resident status. Green cards are typically obtained through family sponsorship, employment, or refugee status. Holders of a green card enjoy many of the same rights as U.S. citizens, but they cannot vote in federal elections. Green card holders must also renew their cards every ten years and can apply for U.S. citizenship after meeting certain requirements, such as residing in the country for a specific period.