Established in 1997, this is a web-based system run by the federal government that allows U.S. employers to determine the eligibility of their employees, both U.S. and foreign citizens, to work in the U.S. The program is voluntary, though there are significant voices in the immigration debate pushing to make it mandatory.

A division of ICE responsible for enforcing federal immigration laws and ensuring the removal of immigrants who are in the country illegally. These special task forces are strategically placed and mobilized in order to carry out their operations—often called “raids”—to locate, apprehend, and remove undocumented immigrants. ERO can also refer to the act of removing an undocumented immigrant from the country.