Trafficking in persons, or human trafficking, was re-defined by the international community in 2001 to incorporate a broader definition that recognizes it as a human rights problem involving forced labour, servitude or slavery among other issues.

Trafficking in persons involves three core elements:
(1) the movement of a person (inside a country or across borders)
(2) with deception or coercion (3) into a situation of forced labour, servitude or slavery-like practices

Trafficking also begins through recruitment, forced migration, purchase, sale or receipt of people. Following movement (whether forced or voluntary), through deception or coercion - including force, the threat of force or debt bondage - a person is then forced into an exploitative situation such as servitude, forced or bonded labour.

In many cases trafficking begins when a person voluntarily decides to migrate, but ends up being trafficked. This can occur whether people move by legal or illegal means. Migrants are often forced by restrictive and complicated immigration laws to rely upon third parties to help them travel or to find jobs in other countries and this can increase the risk of trafficking.

The first international definition of "trafficking in persons" was in 2000, as part of the UN Protocol to Prevent, Suppress and Punish Trafficking in Persons. Especially, Women and Children supplementing the UN Convention against Transnational Organized Crime, also called the Palermo Protocol.

This Protocol defines trafficking in persons as "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 or organs".