If you want to extend your stay in the United States, then you must file a request before your authorized period of stay expires. If you stay in the United States after your authorized period of stay has expired, you may be barred from returning and/or you may be removed (deported) from the United States. You also may be required to apply for a new visa in the country of your nationality.
Naturalization is the process to voluntarily become a U.S. citizen if you were born outside of the United States. In general, you may be eligible if you can show continuous U.S. residence for three to five years, are at least 18 years old, and demonstrate good moral character and loyalty to the U.S. Constitution. You must also take the English and civics test, unless you qualify for an English language exemption or a medical disability exception.
If you were born outside of the United States, there are two general ways to obtain U.S. citizenship through U.S. citizen parents. You can acquire U.S. citizenship at birth or you can derive citizenship from your parents after your birth but before the age of 18.
It is important to keep your Green Card (USCIS Form I-551 or Permanent Resident Card) up-to-date. Without a valid Green Card, it may be difficult for you to prove that you are a lawful permanent resident and could affect your ability to travel or to prove your authorization to live and work in the United States.