A visa is a document issued by the U.S. Department of State (DOS), usually at a U.S. abroad. This document, often called a stamp, is affixed to a page in one's passport. A visa does not guarantee an individual's entry into the United States, nor does the visa confer a U.S. immigration status upon an individual. Instead, the visa allows the holder to request permission to enter the United States at a port of entry (POE)/

Visas may be issued for single entry or multiple entries. Whether or not a visa will be issued for single or multiple entries is dependent upon the category and country-specific issues of reciprocity with the United States. A multiple-entry visa does not have limits on the number of times one may use the visa for travel.

The visa also indicates an issue date and an expiration date. The maximum validity timeframe varies anywhere from one month to ten years, depending upon the visa category. The visa expiration date does not correspond to the length of time an individual is allowed to remain in the United States; the expiration date dictates the last day that the individual can request admission to the United States.