If you are coming to the U.S. on an F-1 student visa, there is an “End Date” on your I-20 Form. On your I-20 form it says: The student is expected to report to the school no later than ______________ and complete students not later than ___________.” That date is an important date. You are expected to finish your program of study by that date. You are allowed to remain in the U.S. for up to 60 days after that date. That 60-day period is referred to as the “grace period.” If you finish your program of study before that date, you will need to discuss it with the Director of International Student Services. Or, if you would like to request more time to complete your program, you need to discuss it with the Director of International Student Services before your program ends.
Your visa needs to be valid at the time you enter the U.S. If it expires while you are in the U.S., that is not a problem. But if you leave the U.S. (for example, during summer vacation) and then plan to return, you will need to renew your visa before you return to the U.S. if it has expired.