What is the Green Card?
Large numbers of people enter the U.S. from other countries on a daily basis. Some people are returning home after being away for some time, some are coming to visit their family, some on a holiday, some for work and some move permanently to settle down in the U.S. Whatever may be the reason, each person who is entering the U.S. should possess the right documents to prove that they are legally allowed to enter the country.
Many people are permitted to enter the country only for a specified time and that too for a specific purpose only. People who are on a vacation to the U.S. may be permitted to enter for a few weeks only and purely for tourist activities. They would not be allowed to work in the US. There are instances where some people would be permitted to enter for a few years at a time for work but this could be restricted to a certain employer. People who are moving to the U.S. under this category are called non-immigrants.
People who live and work in the U.S. without any restrictions are called immigrants. They are permitted to stay in the U.S. for an unlimited period of time, to participate in any legal activity, to work and also to study. Generally, immigrants refer to a select number of foreign nationals who have been permitted to live and work in the U.S. permanently.
Both Immigrants and Non-Immigrants must show a valid visa before they enter the US. A visa is similar to a pass. An immigrant who has gained entry to the U.S. would be issued an Alien Registration Card which is also known as a Green Card. Early editions of the card were light green in color and hence the term. Present day cards are either pink or light blue. A person with a Green Card is called a Lawful Permanent Resident.

