If you're planning a short trip to the United States, you must, with certain exceptions, obtain a "nonimmigrant" (temporary) visa. (For exceptions to this rule, see U.S Immigration Basics, in particular, the discussion of the Visa Waiver Program.)
Below we summarize who qualifies for the various types of nonimmigrant visas. For details, including how to apply for a visa, see U.S. Immigration Made Easy, by Ilona Bray (Nolo).
You must choose the specific purpose of your trip (such as tourism or going to school) and apply for a specialized visa that authorizes that activity and no other. Each type of nonimmigrant visa is identified by a letter-number combination. You may already be familiar with the more popular ones: B-2 (visitor for tourism), E-2 (investor), F-1 (academic or language student), and H-1B (specialty worker). See the chart below for a complete list of the most commonly used codes and descriptions.
A-1. Ambassadors, public ministers, or career diplomats, and their spouses and children.
A-2. Other accredited officials or employees of foreign governments, and their spouses and children.
A-3. Personal attendants, servants, and employees of A-1 and A-2 visa holders, and their spouses and children.
B-1. Business visitors.
B-2. Visitors for pleasure or medical treatment.
C-1. Foreign travelers in immediate and continuous transit through the U.S.
D-1. Crew members who need to land temporarily in the U.S. and who will depart aboard the same ship or plane on which they arrived.
D-2. Crew members who need to land temporarily in the U.S. and who will depart aboard a different ship or plane than the one on which they arrived.
E-1. Treaty traders working for a U.S. trading company that does 50% or more of its business with the trader's home country, and their spouses and children.
E-2. Treaty investors working for a U.S. company with 50% or more of its investment capital coming from the investor's home country, and their spouses and children.
E-3. Australian professionals coming to the United States to perform services in a specialty occupation (similar to an H-1B, but with a separate allotment of 10,500 visas). Spouses and children may accompany the E-3 visa holder.
F-1. Academic or language students.
F-2. Spouses and children of F-1 visa holders.
F-3. Citizens or residents of Mexico or Canada commuting to the U.S. to attend an academic school.
G-1. Designated principal representatives of foreign governments coming to the U.S. to work for an international organization, and their spouses and children.
G-2. Other accredited representatives of foreign governments coming to the U.S. to work for an international organization, and their spouses and children.
G-3. Representatives of foreign governments and their immediate family members who would ordinarily qualify for G-1 or G-2 visas except that their governments are not members of an international organization.
G-4. Officers or employees of international organizations and their spouses and children.
G-5. Attendants, servants, and personal employees of G-1 through G-4 visa holders, and their spouses and children.
H-1B. Persons working in specialty occupations requiring at least a bachelor's degree or its equivalent in on-the-job experience, and distinguished fashion models.
H-1C. Nurses who will work for up to three years in areas of the U.S. where health professionals are recognized as being in short supply.
H-2A. Temporary agricultural workers coming to the U.S. to fill positions for which a temporary shortage of U.S. workers has been recognized by the U.S. Department of Agriculture.
H-2B. Temporary workers of various kinds coming to the U.S. to perform temporary jobs for which there is a shortage of available, qualified U.S. workers.
H-3. Temporary trainees coming for on-the-job training unavailable in their home countries.
H-4. Spouses and children of H-1, H-2, or H-3 visa holders.
I-1. Bona fide representatives of the foreign press coming to the U.S. to work solely in that capacity, and their spouses and children.
J-1. Exchange visitors coming to the U.S. to study, work, or train as part of an exchange program officially recognized by the U.S. Department of State.
J-2. Spouses and children of J-1 visa holders.
K-1. Fiancés or fiancées of U.S. citizens coming to the U.S. for the purpose of getting married.
K-2. Minor, unmarried children of K-1 visa holders.
K-3. Spouses of U.S. citizen petitioners awaiting USCIS approval of their immigrant visa petition and the availability of an immigrant visa, who'd like to enter the U.S. and apply to adjust status, as a supposedly shorter way through the system. (This visa is almost never used, as it tends to actually save no time and cost more.)
K-4. Unmarried children of K-3 visa holders.
L-1. Intracompany transferees who work as managers, executives, or persons with specialized knowledge.
L-2. Spouses and children of L-1 visa holders.
M-1. Vocational or other nonacademic students, other than language students.
M-2. Spouses and children of M-1 visa holders.
M-3. Citizens or residents of Mexico or Canada commuting to the U.S. to attend vocational school.
N-8. Parents of certain special immigrants.
N-9. Children of certain special immigrants or N-9 visa holders.
NATO-1, NATO-2, NATO-3, NATO-4, and NATO-5. Representatives, officials, and experts coming to the U.S. under applicable provisions of the NATO Treaty, and their immediate family members.
NATO-6. Civilians accompanying military forces on missions authorized under the NATO Treaty, and their immediate family members.
NATO-7. Attendants, servants, or personal employees of NATO-1 through NATO-6 visas holders, and their immediate family members.
O-1. Persons of extraordinary ability in the sciences, arts, education, business, or athletics.
O-2. Essential support staff of O-1 visa holders.
O-3. Spouses and children of O-1 and O-2 visa holders.
P-1. Internationally recognized athletes and entertainers, and their essential support staff.
P-2. Entertainers coming to perform in the U.S. through a government-recognized exchange program.
P-3. Artists and entertainers coming to the U.S. in a group to present culturally unique performances.
P-4. Spouses and children of P-1, P-2, and P-3 visa holders.
Q-1. Exchange visitors coming to the U.S. to participate in international cultural exchange programs.
Q-2. (Walsh visas) Participants in the Irish Peace Process Cultural and Training Program
Q-3. Spouses and children of Q-1 visa holders.
R-1. Ministers and other workers of recognized religions.
R-2. Spouses and children of R-1 visa holders.
S-5. People coming to the U.S. to supply information to U.S. authorities about a criminal organization.
S-6. People coming to the U.S. to provide information to U.S. authorities about a terrorist organization.
T-1. Victims of trafficking in persons.
T-2, T-3. Spouses and children of victims of trafficking.
TN. Trade visas for Canadians and Mexicans.
U-1. People who have suffered "substantial physical or mental abuse" as a result of certain U.S. criminal violations including domestic violence and who are assisting law enforcement authorities.
U-2, U-3. Spouses and children of U-1 visa holders.
V. Spouses and children of U.S. lawful permanent resident petitioners who have already waited three years for the approval of their visa petition or for an immigrant visa to become available, so long as their visa petition was submitted on or before December 21, 2000.
For more information on eligibility for employment-based nonimmigrant visas, see Nonimmigrant (Temporary) Work Visa Options. Your next step is determining how and where to apply for your visa. For more information, see Applying for a Nonimmigrant (Temporary) Visa or get the book U.S. Immigration Made Easy, by Ilona Bray (Nolo).
Your visa allows you to enter the United States and to engage in certain activities while you're there. For example, if you receive a student visa, you're allowed to study in the United States, but not to work off campus (unless you seek special permission) and not to stay permanently.
Just as nonimmigrant visas vary in purpose, they also vary as to how long they last. Each nonimmigrant visa is given an expiration date according to what the law allows. Most can also be extended a certain number of times.
An important caution: The expiration date on your visa does not indicate how long you can stay in the U.S. once you arrive. It indicates only the period of time during which you have the right to enter the United States using that visa. How long you can stay is shown by the date on Form I-94, which might be a small white or green card given to you upon entry or (if you entered after April 2013), you can access this record online on the U.S. Customs & Border Protection website.
If your visa is "multiple entry," however, you can use it to enter the United States again, as soon as you like. If it's not multiple entry, you can use it only once. For information about questions you may be asked when you arrive in the U.S., see Entering the U.S.: What to Expect at the Airport or Border.
For a comprehensive resource that covers nearly every way to legally enter and live in the United States, get U.S. Immigration Made Easy, by Ilona Bray (Nolo).