H-1B
The H-1B visa program is used by some U.S. employers to employ foreign workers in specialty occupations that require theoretical or technical expertise in a specialized field and a bachelor’s degree or its equivalent. Typical H-1B occupations include architects, engineers, computer programmers, accountants, doctors and college professors. The H-1B visa also includes certain fashion models of distinguished merit and ability. The current annual cap on the H-1B category is 65,000. Not all H-1B nonimmigrants are subject to this annual cap. The initial visa length is up to 3 years; additionally increments of up to 3 years per extension, with a total stay limited to 6 years.

H-1B1
An H-1B1 is a national of Chile or Singapore coming to the United States to work temporarily in a specialty occupation. The law defines an H-1B1 specialty occupation as a position that requires theoretical and practical application of a body of specialized knowledge. The beneficiary must have a bachelor’™s degree or higher (or equivalent) in the special specialty. The combined statutory limit is 6,800 per year. The initial visa length is up to 3 years; additionally increments of up to 3 years per extension, with a total stay limited to 6 years.

H-2B
H-2B classification applies to temporary or seasonal nonagricultural workers. The H-2B visa category allows U.S. employees in industries with peak load, seasonal or intermittent needs to augment their existing labor force with temporary workers. The H-2B visa category allows U.S. employers to augment their existing labor force when necessary due to a one-time occurrence which necessitates a temporary increase in workers. Typically, H-2B workers fill labor needs in occupational areas such as construction, health care, landscaping, lumber, manufacturing, food service/processing, and resort/hospitality services. As of 2010, an H-2B petition may not be filed more than 120 days before the date of the actual need for the H-2B workerâ€Â™s labor/services identified on the labor certification. As a result, USCIS normally begins receiving H-2B petitions with employment start dates in October and June. The h-2B numerical limit set by Congress per fiscal year is 66,000. The initial length of stay is the same as validity of labor certification, with maximum of 1 year; additionally the extension is the same as validity of labor certification, with increments of up to 1 year, and a maximum total stay limited to 3 years.

H-3
H-3 classification applies to trainees other than medical or academic. The H-3 nonimmigrant visa category is for aliens who are coming temporarily to the U.S. to receive training (other than graduate medical education or training) that is not available in their home countries. The training may be provided by a business entity, academic, or vocational institute. The H-3 nonimmigrant visa category also includes aliens who are coming temporarily to the U.S. to participate in a special education training program for children with physical, mental, or emotional disabilities. There is a limit of 50 visas per fiscal year. The initial visa length for special educational training is up to 18 months; with no extensions. For all other trainees the length of stay is limited to 2 years, with no extensions.