Passport: You should keep your passport valid at all times. Your passport is your own government's permit for you to leave and re-enter your own country. Most passports contain expiration date.
Renewing your passport: Consult your own consulate or embassy in the U.S. to renew your passport. The officials there will tell you what forms and fees, if any, are required. You can find out the contact information for your embassy by going to: www.travel.state.gov
Visa: The visa stamp put in your passport by the U.S. Consulate is to enter the U.S. It does not show how long you can stay here.
Renewing your U.S. visa for re-entry: It is necessary to renew your visa if the visa has expired and you are planning on traveling outside the North American continent. You may renew your visa by visiting the U.S. Consulate in the country that you are traveling to. It is not possible to renew an F-1 visa while you are within the borders of the U.S.
Form I-94 (Arrival/Departure Record): I-94 shows that you have been admitted to the U.S. I-94 is usually stapled onto the U.S. visa page of your passport. It contains an eleven-digit identifying number (called your departure number) the USCIS uses to keep track of your arrival and departure from the United States. The USCIS sometimes refers to the "departure" number as the "admission" number.
Expiration: There should be a date stamped on the I-94 indicating the date that you arrived in the U.S. You should also see that "D/S" is written below the date stamp. This "D/S" indicates "duration of status" which means that you are admitted for the length of your program of study, plus any period of Optional Practical Training, plus 60 days. If you graduate before the completion date indicated on your I-20 you are considered to have completed your program of study and your I-20 is no longer valid.
Form I-20: I-20 is issued for the program and level of study you are presently pursuing. The third page of the I-20 contains spaces for information about the F-1 student’s dependents, employment authorization, and travel signatures by a Designated School Official at UTEP.
Traveling Outside of the United States: All students in F-1 status must have a signature on page 3 of their I-20 from an advisor at Office of International Programs before leaving the United States if they intend to re-enter the United States. The signature is valid for twelve months.
Remember that: Your passport must be valid beyond the date on which you plan to re-enter the U.S. If the visa is valid for only one entry, or has expired, a new visa can be obtained from the U.S. Consulate in the country you are visiting by presenting evidence of financial support and either your current I-20 or a new one as appropriate. You should allow enough time to obtain a new visa. You should go to www.travel.state.gov for requirements to obtain a new visa at a specific consulate or embassy. Exceptions to this rule are for visits to Canada, Mexico, or the Caribbean Islands. For such trips you will need only a passport, your endorsed I-20, and a current Form I-94. You can reach all embassies at: www.travel.state.gov.