Employment-based visas are separated into Five Preference Categories:

• E1 (Employment 1st preference) Priority workers: An E1 applicant must have an approved Immigration petition for foreign workers form I-140 from the U.S. Citizenship and Immigration services completed. Within this category, qualifiers consist of people who are extraordinarily gifted in education, business, art, athletics, or sciences.
• E2 (Employment 2nd preference) Professionals holding advanced degrees and Persons of Exceptional Ability: An E2 applicant must have an approved labor certification from the Department of Labor. There is a requirement that the applicant must have a job offer and that the U.S. employer must file an immigrant petition for alien worker, form I-140, on the applicant’s behalf.
• E3: (Employment 3rd preference) Skilled workers, Professionals, and Unskilled workers (Other workers): An E3 applicant must have an approved immigrant petition for alien worker, form I-140, that has been filed by their U.S. employer. Another requirement is that the person must also have an approved labor certification from the Department of Labor.
• E4: (Employment 4th preference) Certain Special Immigrants: An E4 applicant must have an approved petition for Amerasian, widower, or special immigrant for I-360. These applicants are considered certain special immigrants and may qualify for an E4 work visa; they are not required to have an approved labor certification.
• E5: (Employment 5th preference) Immigrant Investors: An E5 applicant must have an approved Immigrant Petition by Alien Entrepreneur from USCIS. Applicants must be a foreign citizen who invests between $500,000 and $1,000,000 USD in a commercial enterprise that creates full-time jobs for at least ten U.S. citizens, legal permanent residents, or other lawful immigrants.