What is a Green Card?
Green Card through Marriage to a U.S. Citizen
A "green card" is proof of your lawful permanent residence in the United States. It allows you to live and work in the U.S. without any time restrictions whatsoever. If you obtain your green card through marriage to a U.S. citizen, you can qualify to apply for U.S. citizenship three years after you are approved for lawful permanent residence.
Those who quality and apply for a green card while inside the United States are eligible for a temporary employment authorization card while their application is being processed. They may also be eligible for a travel permit, which would allow them to travel in and out of the United States while the application is being processed.
Granting of lawful permanent residence authorizes a foreign national to work in the United States for any employer for any length of time. The green card itself serves as proof of employment authorization. Additionally, you can also freely travel in and out of the United States using your passport and green card. However, you must be careful not be "abandon" your lawful permanent residence by staying outside of the United States for long periods of time.
With the rapidly changing laws of the United States and the current strict political climate towards immigrants, it is increasingly important that one take the time and opportunity to obtain a green card as soon as possible.