Irregular immigration or illegal immigration is the migratory movement of people across borders without complying with the legal requirements of the destination country and sometimes also of the country of origin. A person in this situation is an irregular immigrant , an illegal immigrant , an undocumented immigrant , or simply an undocumented immigrant (without documents such as a residence permit or a work permit).
The term migrant worker has different official meanings and connotations in different parts of the world. The United Nations definition is broad, including anyone who works outside their country of origin. Some of these are also called expatriates. Several countries have millions of foreign workers. Some have millions of irregular migrants, most of whom are also workers.
The term can also be used to describe someone who emigrates from a country, possibly their own, in order to seek work such as seasonal work.
The International Labour Organization estimated that in 2014 there were 232 million international migrants worldwide who were away from their country of origin for at least 12 months, and approximately half of them were economically active (i.e., employed or seeking employment). Some countries have millions of migrant workers. Some migrant workers may be irregular migrants, and some may be slaves.
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