The H-1B is a non-immigrant visa in the United States under the Immigration & Nationality Act, section 101(a)(15)(H). It allows U.S. employers to employ foreign guest workers in specialty occupations. Employers can hire an H1B even if qualified Americans are available.
The regulations define a “specialty occupation” as requiring theoretical and practical application of a body of highly specialized knowledge in a field of human endeavor including, but not limited to, architecture, engineering, mathematics, physical sciences, social sciences, medicine and health, education, law, accounting, business specialties, theology, and the arts, and requiring the attainment of a bachelor’s degree or its equivalent as a minimum. Likewise, the foreign worker must possess at least a bachelor’s degree or its equivalent and state licensure, if required to practice in that field. H-1B work-authorization is strictly limited to employment by the sponsoring employer - except that many H-1B work for bodyshops who then place them with third party employers.
http://en.wikipedia.org/wiki/H1B_visa
http://en.wikipedia.org/wiki/United_States_visas