A green card is, technically, a United States Permanent Resident Card. This card serves as identification for one who is a lawful permanent resident (LPR) of the U.S. Holders of this card may conditionally reside and work in the U.S. This card was previously referred to as the Alien Registration Receipt Card and still may be called form I-551. Although the green card has not been green since 1978, the term remains commonly used.