There are a number of means by which an alien may obtain permanent residence through the sponsorship of an employer, through an investment, or through certain miscellaneous avenues for “special immigrants.” Certain categories require cumbersome labor certification processes while certain preferred categories do not.  In addition, there are numerical limits on employment-based immigrant categories except in certain Treaty categories.  These numerical limits are set each year.  
 
Each employment based category and preference  has been given a symbol by the government, usually beginning with “E” for “employment based, a number for the preference, and another number for the category within that preference. The preferences and categories within them are listed below with their allocation of available employment based Visas.