Adrian Patino (via Flickr)

Migration: definitions and debates in terminology

Frank van Kesteren | 26 November 2015

In order to provide a clear analysis of current international migration flows and policies, clear definitions are required. The key terms used in debates on migration are outlined below. Some terms are followed by short discussions regarding the usefulness of the terms. An explanation on which terminology is used in the Migration Trail living analysis is also discussed.

- Forced migration –  Defined by the International Association for the Study of Forced Migration as ‘a general term that refers to the movements of refugees and internally displaced people (those displaced by conflicts) as well as people displaced by natural or environmental disasters, chemical or nuclear disasters, famine, or development projects’. Therefore, forced migration is used as an umbrella term to describe refugees, asylum seekers, internally displaced persons, development displacees, environmental and disaster displacees, and trafficked and smuggled people.

- Human smuggling – ‘Procurement, in order to obtain, directly or indirectly, a financial or other material benefit, of the illegal entry of a person into a State Party of which the person is not a national or a permanent resident.’ (United Nations, 2000b: Article 3)

- Human trafficking – ‘The recruitment, transportation, transfer, harbouring or receipt of persons, by means of the threat or use of force or other forms of coercion, of abduction, of fraud, of deception, of the abuse of power or of a position of vulnerability or of the giving or receiving of payments or benefits to achieve the consent of a person having control over another person, for the purpose of exploitation. Exploitation shall include, at a minimum, the exploitation of the prostitution of others or other forms of sexual exploitation, forced labour or services, slavery or practices similar to slavery, servitude or the removal of organs.’ (United Nations, 2000a: Article 3)

- Illegal migration – ‘The act of entering a country in contravention to the law which is confined to illegal border crossing (but not overstaying the terms of visas or residence).’ (Kraler and Vogel, 2008: 6)

- Irregular entry – ‘The act of crossing borders without complying with the necessary requirements for legal entry into the receiving State.’ (United Nations, 2000b: Article 3)

- Irregular migration – Migration of someone who ‘at some point in his migration, has contravened the rules of entry or residence.’ (Kraler and Vogel, 2008: 7)

- Refugee – ‘A person who owing to a well-founded fear of being persecuted for reasons of race, religion, nationality, membership of a particular social group or political opinion, is outside the country of his nationality and is unable or, owing to such fear, is unwilling to avail himself of the protection of that country; or who, not having a nationality and being outside the country of his former habitual residence as a result of such events, is unable or, owing to such fear, is unwilling to return to it.’ (UNHCR, 1951: Article 1).

- Transit migration – This term is a sub-category of irregular migration that is difficult to define. Earlier definitions from the International Organization of Migration (2004) for instance imply that transit migration is a short-term phenomenon, with pre-defined routes and without the intention of remaining in the country of transit. However, transit migration is very diverse. Pitea (2010) outlined how policies on transit migration deal with this type of migration through the laws and regulations regarding irregular migration. Therefore, no universal definition can be presented here. For practical matters, transit migration is referred to in its broadest sense as migration that involves a route of more than two countries.

- Undocumented migration – Migration of someone who does not possess the required (and correct) documents to enter a country (Pinkerton et al., 2014). The International Organization for Migration has estimated that 10-15% of the migrants in 2010 were undocumented. (IOM, 2013)

Irregular, illegal or undocumented migration?

Irregular migration is a broader concept in comparison to illegal migration or undocumented migration. Irregular migration has the ability to both analyse the stocks and flows of migration, while illegal or undocumented migration are concepts which can only be used to describe stocks of migrants (Koser, 2005). Moreover, most organizations working on issues of migration use the term ‘irregular migration’, including the International Labor Organization and the International Organization for Migration. For these two reasons, the term irregular migration is used in this living analysis.

Irregular migration or irregular entry?

Although irregular entry always implies irregular migration, irregular migration does not have to suggest that someone contravened the rules of entry. A regular entry can lead to irregular migration if the migrant overstays the visa limit without leaving the country. Similarly, if a migrant violates the restrictions attached to a residency permit, regular entry can become irregular migration.

Human trafficking or smuggling?

Although both trafficking and smuggling are considered criminal activities, the differences between the terms lie in the meanings and purposes. Trafficking involves the use of force, abuse, deception or other forms of action against the will of migrants. Moreover, the purpose of trafficking does not have to be financial profit alone but also sexual exploitation, forced labour or slavery (Triandafyllidou and Maroukis, 2012). Smuggling on the other hand can be a free agreement between smuggler and migrant. The migrant may consider the cooperation beneficial because the person needs the smuggler’s services. In order to use a broader term to refer to organized migration with the help of specialized agents, we use the term smuggling rather than trafficking unless explicitly referring to forced and abusive smuggling.


IOM (2004). IOM Migration Glossary. Geneva: International Organization for Migration.

IOM (2013). World Migration Report. Geneva: International Organization for Migration.

Koser, K. (2005) Irregular migration, state security and human security. Paper for the Global Commission on International Migration.

Kraler, A. & Vogel, D. (2008). Report on methodological issues, Deliverable prepared for the research project CLANDESTINO. Undocumented Migration: Counting the Uncountable. Data and Trends Across Europe. (latest access: 26-10-2015).

Pinkerton, C., McLaughlan, G., & Salt, J. (2004). Sizing the illegally resident population in the UK. London: Home Office.

Pitea, R. (2010). Transit Migration: Challenges in Egypt, Iraq, Jordan and Lebanon. CARIM Research Report. (latest access: 26-10-2015).

Triandafyllidou, A. & Maroukis, T. (2012). Migrant Smuggling. Irregular Migration from Asia and Africa to Europe. London: Palgrave Macmillan.

United Nations (2000a). Protocol to Prevent, Suppress and Punish Trafficking in Persons. Protocol under the United Nations Convention against Transnational Organized Crime. New York: United Nations.

United Nations (2000b). Protocol against the Smuggling of Migrants by Land, Sea and Air. Protocol under the United Nations Convention against Transnational Organized Crime. New York: United Nations.

UNHCR (1951). Convention Relating to the Status of Refugees. New York: United Nations High Commissioner for Refugees.

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