A non-immigrant visa is a permit, affixed or stamped to a page in the bearer's passport, to request entry into the United States. At the port of entry the immigration officer grants admission. A student enters the U.S. under the terms and conditions specified by the particular type of non-immigrant visa that he/she holds. The visa does not determine how long a student can remain in the U.S. A student will need to revalidate his/her visa only if he/she is traveling abroad after the current visa in the passport has expired or an initial I-20 has been issued.
A student who changes non-immigrant status during his/her stay in the U.S. must apply for a new visa abroad in order to re-enter the U.S. in the new status. Please consult the International Student Advisor and the U.S. Department of State web site for further information.