Your passport must be valid at least six months into the future. Report a lost or stolen passport to the police, as your home country government may require a police report before issuing a new passport. To renew or replace your passport, contact your country’s consulate in the U.S. at www.state.gov/s/cpr/rls/fco
An F-1 Visa stamp that the U.S. consular officials place in your passport indicates that you are eligible to enter or re-enter the U.S. as an F-1 student. It does not determine your length of stay in the U.S. If your F-1 Visa expires while you are in the U.S., it is not necessary to renew it as long as you remain in the country. A Visa can only be secured at a U.S. Embassy or Consulate overseas.
An I-20 is issued by the U.S. school you attend and allows you to: 1) apply for an F-1 Visa; 2) enter or re-enter the U.S. to pursue your studies; and 3) receive other immigration benefits. The I-20 lists some recent events such as employment authorization. The I-20 must remain valid at all times throughout your study. You must request a new I-20 prior to the expiration date listed in item #5. You are required to safe keep every I-20 issued to you for your permanent record. Do not discard old ones.
To re-enter the U.S. to resume your studies at CSI after a temporary absence abroad not exceeding 5 months, you must obtain a travel endorsement from the International Student Advisor on page 3 of your I-20.
The I-94 is a small white card, usually stapled into your passport, by an immigration official at the Port of Entry. This card and a valid I-20 permit you to stay temporarily in the U.S. as an F-1 student. The immigration official should indicate "F-1D/S" on your I-94. D/S stands for "duration of status" and refers to the length of time an F-1 student is permitted to remain temporarily in the U.S. to pursue a full course of study. Except for brief visits (30 days or less) to Canada , Mexico and Adjacent, you are issued a new I-94 card with a new admission number each time you enter the U.S.