Employment based citizenship category is widely used by highly skilled immigrants from foreign countries. This category mainly includes IT Professionals, Pharmacists, Other Medical professionals. They come to USA on non-immigrant petition, Work here legally, Pay taxes and are usually in upper 5 percents of income group. These individuals use employment based immigration process. currently this process has over 100000 slots available to use per year, with per country cap of about 9000 applicants.
For example, people from India have 50000 applicants, and people from combodia have 10 applicants, All of combodians will get their applications approved, but only 9000 of Indians will get the benefit for year. rest of the visa slots remain unused for the year.



