A green card is a form of photo identification that shows that a non-citizen is a legal permanent resident of the United States, reports the U.S. Department of Homeland Security. Most immigrants obtain green cards through family members, employers, or their refugee or asylum-seeking status.
Permanent residents of the United States must carry their green cards with them at all times, according to U.S. Citizenship and Immigration Services. Immigrants need green cards to be able to find legal employment, apply for Social Security cards, obtain driver's licenses and return to the United States after a journey to another country. Green card holders must renew their cards every 10 years, or every two years if the immigrant is a conditional card holder, as of 2015. Immigrants lose their green cards if they move abroad permanently, are ordered to leave the country, or complete the naturalization process and become citizens.
Although the U.S. government allows green card holders to work and live in the country, they do not have all the rights of U.S. citizens. Green card holders cannot vote in U.S. elections, and they must live in the United States for at least five years to be eligible for assistance and benefit programs such as Supplementary Security Income, Temporary Assistance for Needy Families, Full-Scope Medicaid and the Children's Health Insurance Program.