The form I-94 is an arrival/departure card issued by the US Customs and Border Protection services. It is a white card placed in the passport of a foreign national when they enter the US. The form is used as a tool to keep track of the arrival and departure of individuals who are not permanent residents or citizens of the country.
The I-94 indicates the immigration status under which one was admitted as well as how long they are authorized to stay in the country (if applicable). Travelers entering the country using Border Crossing Cards, the Visa Waiver Program, the Compact of Free Association or entering the US temporarily as crew members are exempted from signing the form.
Issuance of the form is normally done at a port of entry. The I-94 is issued electronically in sea or airports, but can be issued in either electronic or hard copy format at land ports. This is after screening by a CBP officer.
The I-94 form indicates how long an individual can stay in the country. It is possible to extend one’s stay by applying for it through Form I-539, after which one would be given a new I-94 if the application is approved. In some types of visas such as student visas (F Visa), the duration of stay is listed as D/S, to indicate that the duration of stay is equivalent to duration of status. As long as one is proven to be a student, they would be allowed to stay in the country legally. In this case, no new I-94 is issued.