The vast majority of visitors to the U.S. are intimately familiar with the popular B visa, divided into B-1, for short term business visitors, and B-2, for pleasure, i.e. tourists, and others.
The B visa, named after the law/statute that created it, i.e. INA 212(a)(15)(B), is likely the first U.S. visa that most foreigners acquire. In fact, if you have a ten-year multiple-entry U.S. visa in your passport, it's almost definitely a B-1/B-2 visa.
The B visas allow foreigners holding it to request permission to enter the U.S. to engage in any of the permissible activities that are matched to the B visa. Those activities are listed below, first for B-1, second for B-2.
You will normally be authorized to enter the U.S. for six months. While the time limit can be shortened, it requires the U.S. Customs & Border Protection officer to seek the approval of a supervising officer. [It is important to know that U.S. law does not allow persons to enter the country on one type of visa with the pre-conceived intention of changing to another type of status while in the U.S., e.g. changing from B-2 to F-1 Student. If you're thinking of doing that, read my blog post, Complex US Immigration Laws Frequently Snare Foreigners: The “Pre-Conceived Intent” Doctrine.]
Even if the activities in which you intend to engage in the U.S. appear on the lists below, a CBP officer could wrongly claim that the activity is not a permissible activity and attempt to deny you entry. Alternatively, the CBP officer may allow you entry, but write "NO COS/NO EOS" in your passport. (The acronym "COS" means "Change of Status" while "EOS" means "Extension of Status"). This is the officer's way of preventing your from extending your trip or changing your nonimmigrant plans once inside the U.S., by enrolling in school or marrying a U.S. citizen, to name just a couple of examples.
If you have concerns that CBP may challenge your request to be admitted to the U.S. upon arrival, speak with a U.S. immigration lawyer prior to your trip. The lawyer may be able to provide you with a "pocket letter" to give to the CBP officer, explaining why you are indeed coming to the U.S. for a purpose consistent with the B visa.
Once you're admitted by CBP on your B visa, you may extend your stay by filing for EOS using I-539. That should buy you another six months of frolicking in the U.S. It wouldn't hurt to show proof of funds to support your extended visit to the U.S. Consider using an I-134, or attaching proof of funds consistent with the I-864P, or better yet, asking a U.S. immigration lawyer for some assistance.
Whatever you do, don't just blow your deadline for leaving the U.S. You need to request your extension before the deadline passes. It cannot be even one day late, and it can only be submitted on paper. See my blog post, U.S. Tourists: Don’t Just Blow Your Deadline for Leaving USA.
Again, go ahead and read the lists of permissible activities below to ensure that you're going to be in full compliance with the terms of your visa.
ACCEPTABLE B-1 (BUSINESS VISITOR) ACTIVITIES
Functions or circumstances that have been determined to be acceptable as B-1 business activities include but are not limited to:
1. Commercial transactions that do not involve gainful U.S. employment (e.g. taking orders for foreign goods);
2. Contract negotiation;
3. Installation, service, or repair of commercial/industrial equipment purchased from outside the U.S. and/or training of U.S. workers to perform such services. (Note: typically, contract of sale requires seller to provide such services and B-1 visitor possesses specialized knowledge essential to contract performance consultation with business associates);
5. Participation in scientific, educational, professional or business conventions, conferences, or seminars;
6. Professional entertainers involved in cultural events, paid for and sponsored by a sending country, that will involve public appearance before non-paying audiences;
7. Investors seeking investments that may eventually qualify them for immigrant or E-2 nonimmigrant status;
8. Independent research or professional artistic activity (e.g. music recording, artistic work such as painting, sculpture, or photography) that do not involve income from an US source;
9. Foreign airline employees who meet E visa criteria but are not nationals of a treaty country or of the airlines’ country of nationality;
10. Planning, constructing, dismantling, maintaining or other employment by foreign employer in connection with exhibits at international fairs and exhibitions;
11. Certain religious and charitable activities (e.g. missionaries and recognized international volunteer efforts);
12. Certain athletes who:
a. are professional but intend to receive no salary or payment their than prize money;
b. are individuals or members of a foreign-based team in an internationally recognized sporting activity whose principal place of business is in the foreign country where their salaries typically accrue and seek to enter pay only their incidental expenses;
13. Servants employed abroad of:
a. US citizens residing abroad who return or are assigned to the US on a temporary basis;
b. Foreign nationals who have been accorded B, E, F, H, I, J, L, M, O, P, R or TN nonimmigrant status for temporary activities in the US.
ACCEPTABLE B-2 (VISITOR FOR PLEASURE) ACTIVITIES
Individuals in B-2 status are not restricted to tourist activity or social visits. Other permissible activities include, but are not limited to:
1. Medical treatment;
2. Participation in conferences, conventions, etc. of social or fraternal organizations;
3. Short courses of study incidental to tourist or social activities;
4. Amateur entertainers or athletes who will compete or perform in a non-profit context, without payment except for expenses.
Excerpted from document published by legacy “Immigration & Naturalization Service”, (INS), titled:
Employer Information Bulletin 99-03
Business Visitor Activities (6/00)
UNITED STATES DEPARMENT OF JUSTICE
IMMIGRATION AND NATURALIZATION SERVICE
Office of Business Liaison.
Full document available for download below.