Generally, a citizen of a foreign country who wishes to enter the United States must first obtain a visa, either a non-immigrant visa for a temporary stay, or an immigrant visa for permanent residence. Visitor visas are non-immigrant visas for persons who want to enter the United States temporarily for business (visa category B-1), for tourism (visa category B-2), or for a combination of both purposes (B-1/B-2).
Here are some examples of activities permitted with a visitor visa:
These are some examples of activities that require different categories of visas and cannot be done while on a visitor visa:
Visitor visas will also not be issued for birth tourism (travel for the primary purpose of giving birth in the United States to obtain U.S. citizenship for their child).