Modern Slavery includes the crimes of human trafficking, slavery and slavery like practices such as servitude, forced labour, forced or servile marriage, the sale and exploitation of children, and debt bondage. These are facilitated through online interactions.

• Someone is in slavery if they are:
  forced to work through mental or physical threat
  owned or controlled by an ’employer’, usually through mental or physical abuse or the threat of abuse
  dehumanised, treated as a commodity or bought and sold as ‘property’
  physically constrained or have restrictions placed on his/her freedom

Clearly these definitions relate more easily to the act of slavery or servitude, however, the internet enablement of this harm includes any element of facilitation, such as discussions, exchange of good or services or planning to enslave a person.

https://www.unseenuk.org/modern-slavery/modern-slavery
https://www.app.college.police.uk/app-content/major-investigation-and-public-protection/modern-slavery/definitions/