H-1BEstablished by the Immigration Act of 1990 (IMMACT 90), the H-1B nonimmigrant visa category allows U.S. employers to augment the existing labor force with highly skilled temporary workers. H-1B workers are admitted to the United States for an initial period of three years, which may be extended for an additional three years. The H-1B visa program is utilized by some U.S. employers to employ foreign workers in specialty occupations that require theoretical or technical expertise in a specialized field. Typical H-1B occupations include architects, engineers, computer programmers, accountants, doctors and college professors. The H-1B visa program also includes fashion models. The current annual cap on the H-1B category is 65,000. H-1B Advanced Degree ExemptionThe H-1B Visa Reform Act of 2004, which took effect on May 5, 2005, changed the H-1B filing procedures for FY 2005 and for future fiscal years. The H-1B Visa Reform Act of 2004 also makes available 20,000 new H-1B visas for foreign workers with a Master’s or higher level degree from a U.S. academic institution.Duration of H-1B visa: 

The duration of stay under H-1B visa is 3 years but can be extended to 6 years.maximun extention can be made under following circumstances.
• 1 year extensions if a application of labor certification has been filed and is pending for at least 365 days.
• 3 year extensions can be made if an I-140 has been approved.

Click here for more information