Non-immigrant Visas
B Visa E Visa F/M Visa H Visa
J Visa L Visa R Visa TN Visa
Visa Waiver FAQ    

-H Visa
  Persons going to the United States with the intention of working there temporarily in specific prearranged employment, require a classification H visa.
  The employment must be approved in advance by the Department of Homeland Security, United States Citizenship and Immigration Services (USCIS) in the United States on the basis of a petition, form I-129 filed by the United States employer.
  The H category can also include training.

There are several classifications of H visas, including H-1B (specialty occupation), H-2A and H-2B (temporary or seasonal agricultural and nonagricultural workers) and H-3 (trainee).