B-1/B-2 Non-Immigrant Visa is designed for foreign nationals who are coming to the United States for business (e.g. attending meeting and conventions), tourism purposes or to obtain medical treatment. You may also use the visa for a short-term training if your foreign employer is covering your salary. You are not allowed to use this visa to work in the US and / or to study.
Travelers from certain eligible countries may also be able to visit the U.S. without a visa, under the Visa Waiver Program, which exempt citizens from certain countries from the Visa requirement, provided they are holding a machine readable passport.
These countries include: Andorra, Austria, Australia, Belgium, Brunei, Denmark, Finland, France, Germany, Iceland, Ireland, Italy, Japan, Liechtenstein, Luxembourg, Monaco, Netherlands, New Zealand, Norway, Portugal, San Marino, Singapore, Slovenia, Spain, Sweden, Switzerland, and the United Kingdom.
Visa applications may ONLY be made at a US Consulate in your country of residence. There is a presumption in the law that every Visa applicant is an intending immigrant. In order to overcome this presumption you will have to convince the Consular Officer that you have a residence, which you have no intention to abandon, i.e. that you have binding ties that will insure your return at the end of the trip.
When you come to the US with a B-1/B-2 Visa the Immigration Officer at the port of entry will usually grant you permission to stay (A Status) for a period of up to six months. This Status may be EXTENDED or CHANGED to another status, for example, to H, R, L, E-1, E-2, or F/J/M OR Green Card.