An illegal immigrant is somebody who illegally enters a country and takes up residence there. Immigrants are sometimes referred to as , "the new slave labor", and the status, rights, and morality of illegal immigrants are controversial subjects.
It is estimated that over 50% of US crop workers are illegal immigrants.
People who are persecuted in their original country and then enter a country seeking safety are termed asylum seekers. Both terms are freely used by partisans on either side of immigration policy debates when seeking to characterise immigrants either as legitimate refugees ("asylum seekers") or as uninvited aliens ("illegal immigrants").
Illegal immigration (including "asylum seeking") is largely driven by economic forces, especially globalization. With a single global economy, the need for the free movement of goods and capital also implies the need for the free movement of labour (human capital).