Each immigration document serves a specific function. It can be confusing to deal with so many different requirements. Here are a few definitions that may help.
Certificate of Eligibility
The Certificate of Eligibility is the I-20 Form (for F-1 students) or DS-2019 (for J-1 students) that our office sent you. You used this document to obtain your visa stamp and also to enter the US. You are required to have a valid I-20 or DS-2019 while in the US. Please note the program ending date on the form, which will be in item #5 on the I-20 form and item #3 on the DS-2019. Whenever you travel out of the US and plan to reenter, you will need to get a signature on your I-20 or DS-2019 from the OISS office. These signatures are valid for only 6 months. (Please note that the I-20 form states that the signatures are valid for one year; this is no longer correct).
The I-94 form, also known as the admission/departure record is the white card (approximately 4 inches by 4 inches) that was given to you by the immigration service officer at the airport or border crossing. You should have received an I-94 card when you entered the US and are required to be in possession of one while in the US. This is an important document. The immigration service officer stamped the I-94 card with the date you entered the US. He or she also marked the I-94 card with the classification you were admitted in (i.e., F-1, J-1) and the notation "D/S", which indicates your authorized period of stay. The notation "D/S" stands for "duration of status" and means that you have been admitted to stay in the US until you complete your study program, as long as you maintain a legal status. If you have lost your I-94 card or realize that the notations on it are incorrect, please contact (805)893-2929 or email: email@example.com
Your passport is your certificate of identity and nationality. It allows you to travel in foreign countries and reenter your home country. While in the US you must maintain a valid passport, unless you are exempt from this requirement -- i.e., Canadians, citizens of the Federated Republic of the Marshall Islands and the Federated States of Micronesia. You can extend or replace (if lost) your passport through your home country consulate office in the US. Information on foreign country consulate offices (e.g., mailing addresses, contact numbers) can be found on the web at embassies.
Keep your passport in a safe and easily accessible place in case you need it in an emergency. It is a good idea to make a photocopy of your passport and keep it someplace in case you were to lose your original passport. A photocopy of your passport is not a substitute for an original, but it may assist you in obtaining a replacement from your home country consulate office.
The F-1 or J-1 visa is the stamp in your passport granted to you by the US consulate office abroad. The visa stamp is a preliminary entry permit. You are required to present it to the immigration service officer only when you are entering the US unless you are exempt from this requirement -- i.e., Canadians, citizens of the Federated Republic of the Marshall Islands and the Federated States of Micronesia. The visa stamp includes information such as the visa classification (e.g.F-1, J-1, F-2, J-2), the number of admissions or times you can use it to enter the US (e.g., one , two, multiple) and the expiration date . You are NOT required to have a valid visa stamp while you are INSIDE the US. That is, the visa stamp can expire while you are inside the US and you are considered in valid status. If you exit and plan to reenter the US, you will need a valid visa stamp to present to the immigration service officer upon your return -- except for short trips of 30 days or less to Canada, Mexico and adjacent islands (e.g., Jamaica, The Bahamas, Barbados). You cannot obtain a visa stamp in the US. You can only get the visa stamp at an American consulate office abroad.