People who are granted permanent residency in a country are usually issued some sort of documentary evidence as legal proof of this status. In the past, many countries merely stamped the person's passport indicating that the holder was admitted as a permanent resident or that he/she was exempt from immigration control and permitted to work without restriction. Other countries would issue a photo ID card, place a visa sticker or certificate of residence in the person's passport, or issue a letter to confirm their permanent resident status.
In Canada, permanent residents are issued a photo ID card known as Permanent Resident Card.
In the United States, permanent residents are issued a photo ID card - officially known as a Permanent Resident Card, but unofficially referred to as a "green card".(Wikipedia).