Form I-551 Permanent Resident Card commonly referred to as a Green Card was once  known as Alien Registration Receipt Card. A Green Card is an identification document issued by the United States of America affording non-citizens some of the rights its citizens and giving permanent resident status. Individuals with the permanent resident status have certain privileges as well as obligations.  Green Card holder has to adhere to all requirements to  maintain a permanent residence status and failure to do so may commence removal proceedings.