These kinds of Visas are nonimmigrant visas issued to people entering U.S. temporarily for business (B1), or for pleasure/visiting medical treatment (B2). Generally these visas are valid for five to ten years. No matter how long your visa is valid you are allowed to legally stay in the US only for the duration mentioned on your I-94. I 94 is issued to you when you enter US. You must leave United States or apply for an extension of stay in the US prior the expiration of your I-94. Failure to extend the visa or return home can result in the current visa being revoked and future visa applications being denied.
HOW TO APPLY FOR A VISITOR VISA
You should apply for your visitor visa at the American Embassy or
Consulate with jurisdiction over your place of permanent residence.
You may also apply at any U.S. consular office abroad. However, it may
be more difficult to qualify for the visa outside the country of your
permanent residence.
DOCUMENTATION YOU WILL NEED
- All applicants need Form DS 156 and all male applicants between the ages of 16 – 65 needs to fill in DS 157 in addition to the DS 156. Blank forms are available without charge at all U.S. consular offices;
- A passport valid for travel to the United States and with a validity date at least six months beyond the applicant's intended period of stay in the United States. If more than one person is included in the passport, each person desiring a visa must make an application;
- Two photographs 1 and 1/2 inches square (37x37 mm) for each applicant, showing full face, without head covering, against a light background.
Optional Documentation
you should also be able to prove that you are properly classifiable as
a visitor under U.S. law. Evidence must show;
- The purpose of the trip,
- Intent to depart the United States, and
- Arrangements made to cover the costs of the trip may be provided.
If you are traveling to the U.S. on business, you can present a
letter from the U.S. business/Firm/Company stating the business
purpose of the trip, the intended length of stay and the companies'
intent to reimburse travel costs.
If you are traveling to the U.S. for pleasure/tourist, you can use
letters from relatives or friends in the U.S. whom you plan to visit.
If you are traveling to the U.S. for medical treatment you should have
a statement from a doctor or institution stating the proposed medical
treatment you are required to take in US.
All applicants who do not have sufficient financial funds to support
themselves while in the U.S. must present evidence that someone in the
US will provide support. Visitors are not allowed to accept employment
during their stay in the U.S.
ADDITIONAL INFORMATION
If your passport contains a previously issued visitor visa, you can
inquire about special expedited procedures (available at most consular
offices) for issuance of a new visitor visa. Unless previously
canceled, a visa is valid until its expiration date. Therefore, if you
have a valid U.S. visitor visa in an expired passport, you can use it
along with your new valid passport. You should NOT typically need to
hire professional help in order to prepare documents or securing
access to the U.S. consular office.
Temporary Employment Visas
http://uscis.gov/graphics/services/tempbenefits/TempWorker.htm





