A term defined in ILO Convention No. 182. These forms of child labour must be prohibited for all people under the age of 18 years and includes the following:

• All forms of slavery or practices similar to slavery, such as the sale and trafficking of children, debt bondage, serfdom and forced or compulsory labour, including forced or compulsory recruitment of children for use in armed conflict;
• Using, procuring, or offering a child for prostitution, the production of pornography, or for pornographic performance;
• Using, procuring, or offering a child for illicit activities—in particular, for the production and trafficking of drugs as defined in the relevant international treaties; and
• Work which, by its nature or because of the circumstances in which it is carried out, is likely to harm the health, safety, or morals of the child.

See also Hazardous work.

The 4Ws are a coordination tool used to provide key information regarding which organizations (Who) are carrying out which activities (What) in which locations (Where) in Which period (When). This information is essential to child protection and other sector cluster coordinators and organizations to coordinate their activities effectively and ensure that humanitarian needs are met without gaps or duplication. The 5Ws add the element of "for Whom" to the 4Ws.