Non-immigrant visas
U.S. Business or Tourist visa
Follow this link for official information about U.S. visa policy and procedures: http://www.uscis.gov/graphics/services/tempbenefits/BusPleasure.htm
B-1 Visa – Business: The definition of "business" in this instance is limited, and does not generally allow for gainful employment or productive activity such as operating a business or consultancy work. Specifically, in the applicable U.S. law the term "business" is limited to the negotiation of contracts, consultation with business associates, litigation, and participation in scientific, educational, professional or business conventions, conferences or seminars and other legitimate activities of a commercial or professional nature. It does not include local employment or labor for hire.
B-2 Tourism/Pleasure: In general, persons traveling to the U.S. on holiday or vacation require valid B-2 visas. Only those eligible for visa free travel under the Visa Waiver Program or nationals of a country that has an agreement with the United States allowing their citizens to travel to the United States without B-2 visas have exceptions to this rule, and those must have machine-readable passports from an eligible country. If you are not eligible to travel visa-free, or are not a national of a country where B-2 visa requirements are waived, you will be required to apply for a visa before traveling.
Note: It is the responsibility of the traveler to ensure that he or she is correctly documented for travel. Failure to obtain a visa before traveling may result in you being denied boarding by the airline.
Persons Holding Valid B1/B2: If you already have a multiple entry unexpired B1/B2 visa in your expired passport, that visa is still valid for travel to the U.S. You must carry both the old passport with the visa and an unexpired passport of the same nationality as the expired one.