This term refers to the persons that migrate to any country without a passport and the specific visa if required to enter the country where its desired to migrate.
It also covers the situation of people that stays in a country without the permits needed to live in that country when the visa expires.
Explanation:
This illegal immigration is highly costly for both governments that are involved in the migration. Meaning that the homeland of the migrant has to design and implement controls to prevent this undocumented migration to happen and the country of destination have to use part of the national budget to strength borders.
Historically this migration has been seeing as a risky way to enter a country. In the United States people that take this risk can be harmed or death because they have to endure severe conditions to make the travel inside the United States.
