Applicants who believe they are entitled to immigrant status based in proposed employment in the United States must have their prospective employer file Petition Form I-140 with the USCIS in the United States. Prior to filing a petition the proposed employer must also obtain certification from the U.S. Dept. of Labor, to certify that there are no qualified workers available for the proposed employment in the United States.
In general any applicant for an immigrant visa must be the beneficiary of an approved petition. Certain applicants such as priority workers, investors, certain special immigrants, and diversity immigrants can petition on their own behalf. All other intending immigrants must have a relative or potential employer petition for them.
See the employment-based visas page for further information.