What are the main requirements for an H-1B visa?

The main requirements for an H-1B visa are:

1) The job must be either in a "specialty occupation", i.e., a professional field, or as a fashion model.

• a "specialty occupation" is one which requires the theoretical and practical application of a body of highly specialized knowledge to fully perform the occupation and requires completion of a specific course of education culminating in a baccalaureate degree in a specific occupational specialty, e.g., architects, teachers, engineers, scientists, etc. 
• fashion models, on the other hand, do not have to meet the specialty occupation requirements; instead, they must establish that they possess "distinguished merit and ability," e.g., national or international renown, etc.

2) The applicant must actually have the necessary credentials, e.g., the baccalaureate degree in the particular specialty. 

• If a license is required to practice the particular occupation, then the applicant must possess the necessary license.