If you are a citizen of a foreign country, in most cases you will need a visa to enter the United States. It is the purpose of your intended visit to the US that determines what visa options are available to you.
A visa, however, does not automatically permit entry to the US; it simply indicates that your application has been reviewed by a US consular officer at an American embassy or consulate, and that the consular officer has determined that you are eligible for the visa classification for the specific purpose you sought. Consular affairs are the responsibility of the US Department of State.
While the visa allows you to travel to the United States, it only gets you as far as the port of entry (airport or land border crossing) and allows you to ask an immigration officer to allow you to enter the country. Only an immigration officer has the authority to permit you to enter the US. He or she decides in what status to admit you and how long you can stay for any particular visit. Immigration matters are the responsibility of the US Department of Homeland Security.
As we noted above, it is the purpose of your travel to the United States that determines the appropriate visa category for you. There are two main categories of visas, immigrant and nonimmigrant, that you can apply for.
Purpose of Visit? How does it determine the best visa category for me?
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