First, the employer must determine which category of employment-based visas the foreign national is eligible, such as EB-1, EB-2, EB-3, or EB-4. Second, the employer must determine if a labor certification from the Department of Labor is required and if so, have the certification approved prior to filing a petition for employment-based immigration with the United States Citizenship and Immigration Services (USCIS).
There are a number of temporary work visas available for foreign nationals engaged in specialty occupations. A brief, but non-exhaustive list includes those for foreign nurses, trainees, intracompany transferees, temporary or seasonal agricultural and non-agricultural workers, individuals with extraordinary abilities in the arts, sciences, education, and business, and participants in international cultural programs.
PERM is the process employers must use to apply for permanent labor certification from the Department of Labor (DOL) for foreign nationals they seek to hire for permanent, full-time employment in the U.S. As part of the PERM process, regulations were passed that require employers to conform to specific standards in the certification process, including in their recruitment efforts. See Title 20 of the CFR, Part 656 for a complete list of the PERM regulations.
You can stay and work in the U.S. for three years with an H-1B visa. Sometimes you can get permission to stay for another three years. But after six years, you will have to leave the U.S. and not return for an entire year before you can apply for another H-1B visa.