A commercial transaction that involves the exploitation of a child.  CSEC may involve and against children and amount to forced labour and a form of as well as offering the sexual services of children for compensation, financial or otherwise.

A declaration of the World Congress against Commercial Sexual Exploitation of Children, held in Stockholm in 1996, defined CSEC as:

'sexual abuse by the adult and remuneration in cash or kind to the child or a third person or persons. The child is treated as a sexual object and as a commercial object.’

CSEC includes and other forms of transactional sex where a child engages in sexual activities to have key needs fulfilled, such as food, shelter or access to education. It includes forms of transactional sex where the sexual abuse of children is not stopped or reported by household members, due to benefits derived by the household from the perpetrator. CSEC also potentially includes involving children under the , where the child has not freely consented to marriage and where the child is sexually abuse.

The (NCMEC) states that roughly one out of every five girls and one out of every ten boys will be sexually exploited or abused before they become of age. says that child sexual exploitation is "one of the gravest infringements of rights that a child can endure".