A green card, officially known as an Alien Registration Receipt Card, is the document that allows an immigrant and his or her immediate family to live and work in the United States for the rest of his or her life. To get a green card, you must be sponsored by a relative or employer, go through the green card lottery, get it by asylum, or one of a few other less common means. The following guides will tell you what you need to know about getting a green card.