Final answer:
Foreign nationals seeking to enter the U.S. temporarily use non-immigrant visas, with B-2 visas for tourism and E-2 visas for investors. There are various visas for different purposes, including those for family reunification.
Step-by-step explanation:
The visa used by foreign nationals seeking to enter the United States for a specific purpose that can be accomplished during a temporary period is commonly known as a non-immigrant visa. There are various types of non-immigrant visas, each designed for a specific purpose, such as tourism, business, study, or temporary work.
Foreign tourists visiting the United States typically use a B-2 tourist visa, while foreign investors who wish to make direct investments in the U.S. economy may use an E-2 treaty investor visa. Other non-immigrant visas cater to different temporary purposes such as bringing family members to the U.S. under specific circumstances, where citizens generally get priority when petitioning to bring family members permanently to the country.