A Notice to Appear is a Department of Homeland Security document (Form I-862) issued to a noncitizen whom the federal government believes to be removable from the United States. It starts removal proceedings against noncitizens in the United States by setting forth charges against them. The NTA requires the noncitizen to appear before an immigration judge who will determine whether they should be removed from the United States, allowed to remain in the United States, or allowed to depart voluntarily.
Once an NTA has been issued, the nonimmigrant must appear in immigration court or take another appropriate action in response to the NTA. They cannot ignore the notice and simply leave the United States on their own. Failing to respond to the NTA or leaving the U.S. on their own will result in the person being removed in absentia and bar that person from reentering the United States for five years.