A visa is a permit for a person to apply to enter the United States. Most citizens of foreign countries need visas to enter the United States. The U.S. Department of State, which issues viass to citizens and residents for use during entry to the U.S., operates embassies and consulates in many countries worldwide.
A visa does not confer the right to enter the U.S.; it merely indicates that an individual’s application was reviewed by a U.S. consular officer and that the officer determined that the individual is eligible to apply for admission to the U.S. to engage in a specific activity. Then, during the application process for admission to the U.S., an immigration officer decides whether to allow that person to actually enter. The immigration officer must ask a few questions to confirm the individual’s intentions.
Once the immigration officer decides to grant admission, the officer handwrites the end of the “authorized stay” on the Form I-94 Arrival/Departure Record (a green or white card). Thus, a person’s visa is of little importance while in the U.S., while the I-94 Card is of the utmost importance to the person, because it shows that the person was inspected and admitted, the type of activities in which the person is permitted to engage while in the U.S., and the date by which he or she must leave. Individuals should immediately check their I-94s for errors (such as the wrong date or visa code) and then should ensure that the I-94 is securely stapled to the passport so that it is not lost. An individual must hand in the I-94 during departure from the U.S. so that the immigration authorities know that you left the U.S. on or before the end of the authorized stay. Serious consequences may arise if you remain in the U.S. past the date on the I-94 Card, which is called “overstaying.”
For further information, please visit Fermilab’s Visa Office.