The terms trafficking and smuggling are often used as loosely interchangeable words to describe the illegal child migration business. But trafficking is clearly prohibited by international law, although there is no common international definition. It is defined by a European Union Joint Action as "any behavior that facilitates the entry into, transit through, residence in or exit from, the territory of a Member state, for the purposes [of] sexual exploitation in relation to a child".

The UN Special Rapporteur on the sale of children considers the following definition to be the most workable: "Trafficking consists of all acts involved in the recruitment or transportation of persons within or across borders, involving deception, coercion or force, debt bondage or fraud, for the purpose of placing persons in situations of abuse or exploitation, such as forced prostitution, slavery-like practices, battering or extreme cruelty, sweatshop labour or exploitative domestic servitude." (See the report of the Special Rapporteur on the sale of children 1999; and the UN Optional Protocol to the Convention on the Rights of the Child on the Sale of Children, Child Prostitution and Child Pornography, UN General Assembly, 25 May 2000.)

Where IRIN has used the term smuggling in this report, it has no international legal definition, but refers to the illegal transportation of children for profit. The term trafficking has been avoided, but the research did show that in many cases the smuggling business in Somali children included trafficking, as defined by the UN Special Rapporteur.