This document provides an overview of U.S. immigration law, including the different government agencies involved, various temporary and permanent visa options, and issues of concern for foreign nationals. It discusses temporary work visas like H-1B and L-1 visas as well as the process for obtaining permanent residency or a "green card" through labor certification or other exemptions. It also outlines the stages of green card processing and challenges like quota backlogs that can cause delays.