The United States Permanent Resident Card (Green card) – an identity card or so-called identification card confirming the presence of a residence permit for a person who is not a US citizen, and giving an opportunity for employment.
The permanent resident card serves as proof that its holder is a legal immigrant having similar constitutional rights as all other Americans.
Green card holders are statutorily entitled to U.S. citizenship after showing by a preponderance of the evidence that they, inter alia, have continuously resided in the United States for at least five years. Those who are younger than 18 years old automatically derive U.S. citizenship through at least one of their American parents.
Lawful permanent residents (green card holders) have certain rights by the United States Citizenship and Immigration Services (and other federal agencies). You can reside permanently in the United States, join and serve in the United States Armed Forces, including in many law enforcement agencies, work anywhere in the United States (with the exception of most federal jobs and some companies under contract by the federal government), be protected equally by the law of the United States, their State of residence, and local jurisdictions.