For most people who wish to visit the United States as a visitor for business, pleasure (such as tourism), or medical treatment, their first stop will have to be a U.S. consulate, where they will need to apply for a “B” or visitor visa. However, you may be able to avoid this if you meet all of the following criteria:

• You come from a country that is on the State Department’s list of Visa Waiver Program (VWP) participating countries. These countries have agreements with the United States allowing easy travel back and forth, based in part on the country having a low rate of citizens violating U.S. immigration laws or overstaying their visas.
• You yourself have not violated the terms of any past nonimmigrant visa (for example, by staying in the U.S. beyond the time your previous permitted stays under a visa and I-94 expired), nor have you otherwise become inadmissible (for example, because you have contracted tuberculosis, abused drugs, or committed crimes or security violations.
• You would like to visit the United States for no longer than three months (90 days) as a visitor for either pleasure or business.
• You do not intend to stay in the U.S. permanently.
• You will not be entering the U.S. via a private aircraft or other non-VWP approved air or sea carrier.
• You have not been present in the countries of Iraq, Iran, Libya, Somalia, Syria, Sudan, Yemen (2018 list), or any other country that DHS later designates as supporting terrorism or "of concern" at any time on or after March 1, 2011 (unless you meet an exemption based on performing military service in the armed forces of a VWP country or carrying out official duties in a full-time capacity in the employment of a VWP country government). The Department of Homeland Security (DHS) may lift this exclusion for reasons to do with U.S. law enforcement or national security interests. (This requirement was added December 15, 2015.)
• You are not a national of Iraq, Syria, Iran, or Sudan (even if you carry the passport of another country). To learn whether you are a "national" of one of these countries, you will need to research its laws. The most likely situation would be if you or your parents were born there. (This requirement was also added December 15, 2015.)

If all the above things are true of you, you may skip applying for a visa, and enter the United States under the Visa Waiver Program (VWP). (Created by Section 217 of the Immigration and Nationality Act.)

You will want to weigh the advantages and disadvantages first, however. Even people from Visa Waiver countries sometimes choose to apply for a tourist (B-2) visa first, as it offers the possibility of a longer stay and other protections.

How Long You Can Stay in the U.S. on a B-2 Visa Compared to on the VWP

If you enter the United States on a visa waiver, your maximum stay will be 90 days. With a B-2 tourist visa, by contrast, you will normally be allowed to stay for up to six months. What’s more, with a B-2 visa, you can apply to extend your stay even longer. (See How to Extend Your Stay or Change Your Status While on a B Visa.)

What Rights VWP Entrants Give Up

People who obtain an actual B-2 tourist visa before they enter the United States will enjoy rights to:

• a hearing in front of an immigration judge of the Executive Office of Immigration Review (EOIR) if the U.S. government decides it wants to remove them (deport or send them home), and
• request an extension of their visit or a change to a different nonimmigrant (temporary) visa status, all without leaving the United States.

You don’t receive these basic rights if you enter the U.S. using the Visa Waiver Program. The program is based on a very simple concept: You can easily enter for a 90-day stay, but when those 90 days are over, the U.S. government will have an easy time insisting that you leave.

There are limited exceptions to this 90-day stay rule. If, for example a medical or other emergency arises, or if you fear persecution in your home country, you can request a longer stay, or apply for asylum.

Also, if you become the immediate relative of a U.S. citizen (most likely by marriage, or because you are the minor unmarried child or parent of a U.S. citizen) you will probably be able to apply for a green card (adjustment of status) while in the U.S. on the VWP--on one condition. Applying for the green card cannot have been your original intent when you entered the U.S. under the VWP, or your false statements upon entry could disqualify you from receiving U.S. lawful permanent residence (a green card). Also see the caution on changing USCIS policy in this area in When Adjustment of Status Is Possible for the Immigrant Spouse of a U.S. Citizen.

VWP Entries Do Require Some Documents

Although you can avoid making a stop at a U.S. consulate to get a visa, coming to the U.S. under the VWP does require advance preparation. You will need to:

• obtain a valid passport from your home country, with an expiration date at least six months past the end of your expected U.S. stay, as well as a scannable, electronic chip containing your biometric information (thus making it an an e-passport)
• buy a return ticket to your home country, or a ticket to some other foreign country, unless you will be arriving in your own vehicle
• apply for and receive authorization through the U.S. State Department’s Electronic System for Travel Authorization (ESTA), prior to departing for your trip
• gather evidence that you have enough money to support yourself while in the U.S. without taking a job here
• paying a fee, if you arrive at a land border.

Before you arrive from a Visa Waiver country, the airline, bus, ship company, or other carrier will give you a form to fill out called an I-94W. This is mostly for the purpose of determining whether you are inadmissible to the United States. (To understand the concept of inadmissibility, see Inadmissibility: When the U.S. Can Keep You Out.)

Answering Questions at U.S. Border or Port of Entry

When you arrive in the U.S., the Customs and Border Patrol (CBP) officer will take a look at your I-94W Form and other documents. The officer will see whether your name shows up in an electronic database indicating that you have overstayed any past visas or have a history of criminal, espionage, or terrorist activity.

CBP officers have the power to deny any person entry to the United States if they are not satisfied that he or she fits the criteria for entry and is admissible. They can insist that you return home immediately, without a court hearing or other second opinion. (Learn more about what to expect at the U.S. entry point or border.)

People who enter on tourist visas run this same risk upon entry. At least they, however, have given their application for entry a “trial run” past a U.S. consular official, who would probably have spotted the same issue and denied the B-2 visa right then, thus saving them a long trip to the United States.

There is one good thing about being denied U.S. entry as a Visa Waiver entrant: You can come back anytime, and again request entry. That’s different than many people who arrive with visas, who have to wait five years if refused U.S. entry. However, you would still have to leave the United States before returning.