What is migration?
Migration is where a person moves from one country to another. It can be by legal or illegal means and it can be either voluntary (with the consent of the person migrating) or forced (without their consent), but usually it is voluntary. Displacement of persons and trafficking are examples of forced migration.
 
A migrant is someone who leaves her/his community or country of origin to live, and possibly work and/or marry in another place. “Migrant” is an overarching term that covers many categories of migrants, including refugees, trafficked and undocumented persons and migrants who are in a smuggling situation.

What is smuggling?
According to the UN Protocol against the Smuggling of Migrants by Land, Sea and Air, "Smuggling of migrants" means the 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.

An individual may voluntarily engage the services of a smuggler, but increasingly be drawn into a web of exploitative relationships in order to pay off the debts they incurred in the process. If the individual falls into a situation of debt bondage, it can become a case of human trafficking.
 
GAATW publication on Smuggling:

What is trafficking in persons?
Trafficking in persons, or human trafficking, was re-defined by the international community in 2001 to incorporate a broader definition that recognises 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".

What is child trafficking?
Child trafficking is defined as the movement of a person (18 years and younger), into a situation of exploitative work such as forced labour or slavery-like practices.

This definition is significantly different from the Trafficking in Persons, which is comprised of three core elements: the movement of a person (inside a country or across borders), with deception or coercion, into a situation of forced labour, servitude or slavery-like practices. The definition for child trafficking reflects the vulnerability of children and the special rights set out by international conventions for their protection.

Like adults, children are trafficked for many reasons including begging, work on construction sites, agricultural work, sexual exploitation and for domestic work.

Child trafficking is included in the ILO Convention Concerning the Prohibition and Immediate Action for the Elimination of the Worst Forms of Child Labour definition of the term "the worst forms of child labour", which includes:
(a) all forms of slavery or practices similar to slavery, such as the sale and trafficking of children, debt bondage and serfdom and forced or compulsory labour, including forced or compulsory recruitment of children for use in armed conflict;

(b) the use, procuring or offering of a child for prostitution, for the production of pornography or for pornographic performances;
(c) the use, procuring or offering of a child for illicit activities, in particular for the production and trafficking of drugs as defined in the relevant international treaties;
(d) work which, by its nature or the circumstances in which it is carried out, is likely to harm the health, safety or morals of children.

What is slavery?
Slavery-like practices are prohibited by the 1956 UN Supplementary Convention on the Abolition of Slavery, the Slave Trade and Practices similar to Slavery. The Convention does not contain a definition of slavery, but does list a number of practices and institutions that constitute slavery-like practices such as debt bondage, serfdom, forced and early marriage, and the exploitation of children and adolescents.

Two common criteria can be derived from the listed examples:
- the infringement of the formal or de-facto legal status of a person, resulting in a serious and far-reaching deprivation of fundamental rights, in combination with
- the one-sided economic exploitation of the person through the abuse of long-term relations of dependency.
SOURCE: GAATW and Anti-Slavery International:

http://www.antislavery.org/english/slavery_today/what_is_modern_slavery.aspx

What is forced labour?
Forced labour and slavery-like practices are the extraction of work or services from any person or the appropriation of legal identity and/or physical person by means of violence or threat of violence, abuse of authority or dominant position, debt bondage, deception or other forms of coercion.

In Article 2 of the ILO Forced Labour Convention, "forced or compulsory labour" means all work or service which is exacted from any person under the menace of any penalty and for which the said person has not offered himself voluntarily.

What is exploitation? 
Partially defined in Article 3 (a) of the UN Trafficking Protocol (Palermo Protocol, 2000): "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." No agreement was achieved when the UN Trafficking Protocol was being discussed on the precise definitions of the terms ‘sexual exploitation' and ‘exploitation of the prostitution of others'.

What is debt bondage?
Debt bondage is "the status or condition arising from a pledge by a debtor of his personal services or of those of a person under his control as security for a debt, if the value of those services as reasonably assessed is not applied toward the liquidation of the debt or the length and nature of those services are not respectively limited and defined" - as defined in Article 1 (a) of the 1956 UN Supplementary Convention on the Abolition of Slavery, the Slave Trade and Practices similar to Slavery.

What is demand?
Demand is a term used in reference to sex work, to describe the needs or wants of clients who frequent sex workers.

Current international discussion about the "demand" for human trafficking is extremely narrow, focusing only on trafficking for sexual exploitation and does not address other forms of trafficked labour (forced or exploitative). Within this narrow perspective, the discussion is limited to the role and demand of the clients of sex workers, and does not address the role or the responsibility of states and the private sector.

The term demand can more accurately refer to globalisation and the demand for cheap, exploitable labour and services in many countries, particularly those in the global north. In destination countries there is a growing need for unskilled and labour intensive work in order to be able to compete with low wage countries. This work is mostly done by irregular and unprotected migrant workers. Both governments and corporations are accountable for this exploitative situation and should take responsibility to change it. Not least, we as consumers have a responsibility to stimulate and support fair trade and perpetuate awareness around this issue.

GAATW publications on the demand side of trafficking:

 

All definitions come from GAATW documents and publications unless otherwise stated, particularly publications include: Human Rights and Trafficking in Persons: A Handbook, GAATW (2001) and Trafficking in Women, Forced Labour and Slavery-Like Practices in Marriage, Domestic Labour and Prostitution; STV, GAATW (1999).