All About B1 Visa

In most cases, a foreign national who wishes to come to the United States must first obtain a visa. There are two types of visas: a nonimmigrant visa for those who wish to enter the country on a temporary basis, or an immigrant visa for those coming to this country for obtaining permanent residency. A visa allows a foreign national to travel to a port-of-entry in the United States, requesting permission of a U.S. immigration inspector to enter the U.S.

More info at http://www.immigrationdirect.com/visas/visitor/b1-business-visa.jsp