US Nonimmigrant Visas
The visa stamp allows you to travel to a US Port of Entry and request permission to enter the country. The category of your visa relates to the purpose of your travel (study, work, tourism, etc.) and often requires supporting documentation. The valid visa does not guarantee your entry, but shows that you are currently eligible for that status. When you are admitted to the United States, a Form I-94 Arrival/Departure Record will be created for you, annotated with the category and expiration of your status. You will find more detailed answers to frequently-asked visa questions and a sample image of the US visa through the Bureau of Consular Affairs.
The visa is only required when you are entering the country and may expire while you are here, without any impact to your US immigration status or permissions. However, if your visa stamp expires, you will need to plan enough time during your next trip abroad to apply for a renewed visa stamp prior to your return (excluding re-entry using Automatic Revalidation for eligible travelers). It is NOT possible to apply for or renew your US visa while you are in the United States. Please visit the US Department of State for more visa information and up-to-date requirements.
Procedures & Information
Additional information and other resources are also available for: