The non-immigrant visa classification covers a broad range of visas used to enter the United States for work, pleasure or study. Some visas are considered ‘dual status’; you may attempt to obtain permanent residency (a green card) while under that classification. Most non-immigrant visas, however, require you establish the demonstration of non-immigrant intent. This means you should demonstrate that you have a permanent residence in your home country that you have no intention of abandoning. The duration of time you may spend in the US can range from a few days to several years, depending on the visa. In most situations, your spouse and unmarried children under the age of 21 may accompany you on a derivative visa.
As of October 17, 2008 Nationals (i.e., citizens) of 34 countries do not need to obtain B visas for business or tourist visits to the United States of 90 days or less provided certain conditions are met. The countries are Andorra, Australia, Austria, Belgium, Brunei, Denmark, Finland, France, Germany, Iceland, Ireland, Italy, Japan, Liechtenstein, Luxembourg, Monaco, the Netherlands, New Zealand, Norway, Portugal, San Marino, Singapore, Slovenia, Spain, Sweden, Switzerland, United Kingdom, Czech Republic, Estonia, Latvia, Lithuania, Hungary, The Republic of Korea, and Slovakia Republic (note that, under a different rule, visas are not required for Canadian citizens, some Canadian permanent residents, and a few other groups).