There are six different types of H (temporary worker or trainee) visas. These are:
(1) Specialty Occupation (H-1B): An H-1B visa is available to an alien who, subject to INA § 212(j)(2) [8 U.S.C.A. § 1182(j)(2) ] pertaining to limitations on the immigration of foreign medical graduates, is coming temporarily to the United States to perform services in a specialty occupation, meets certain specified requirements for the occupation, and with respect to whom the Secretary of Labor determines and certifies to the Secretary of the Department of Homeland Security that the intending employer has filed a prescribed application with the Labor Department
(2) Professional Registered Nurse (H-1C): An H-1C visa is available to an alien who is coming temporarily to the United States to perform services as a registered nurse, meets the required qualifications for an alien coming to the United States to perform nursing services for a facility (described in INA § 212(m)).
(3) Temporary Agricultural Worker (H-2A): An H-2A visa is available to an alien who, having a residence in a foreign country which he or she has no intention of abandoning, is coming temporarily to the United States to perform agricultural labor or services of a temporary or seasonal nature
(4) Skilled/Unskilled Worker (H-2B): An H-2B visa is available to an alien who, having a residence in a foreign country which he or she has no intention of abandoning, is coming temporarily to the United States to perform other than agricultural temporary service or labor, if unemployed persons capable of performing such service or labor cannot be found in the United States.
(5) Trainee (H-3): An H-3 visa is available to an alien who, having a residence in a foreign country which he or she has no intention of abandoning, is coming temporarily to the United States as a trainee, other than to receive graduate medical education or training, in a training program that is not designed primarily to provide productive employment.
(6) Spouse or minor child (H-4): An H-4 visa is available to the non-citizen spouse or minor child of any non-citizen holding an H visa. Some H-4 visa holders are authorized to work in the United States.
H nonimmigrants must be inspected by an immigration officer at a port of entry. Generally, the non-immigrant must present an unexpired passport valid for a minimum of six months from the date of the expiration and a valid unexpired visa to the immigration officer.