A nonimmigrant is a foreign citizen who visits the United States for a temporary purpose – tourism, work, or study – and, when finished, leaves the United States. Before being permitted to visit the United States as a nonimmigrant, foreign citizens must prove their nonimmigrant intent.

When non-immigrants apply to visit to the United States, they must declare their primary purpose for visiting. Non-immigrants must declare this purpose at least twice: once when applying for a visa at a United States embassy or consulate and again at the U.S. port-of-entry (POE) where they arrive in the United States. The declared primary purpose determines the type of visa needed and the nonimmigrant class of admission when admitted at the POE.

An F-1 nonimmigrant status, therefore, is granted to individuals whose main purpose for entering the United States (U.S.) is to complete a full course of study and then return to their home country upon completion of their studies.

For more information, please view: http://www.ice.gov/sevis/becoming_nonimmigrant_student_52007.htm