In base game RimWorld is limited only to selling prisoners for profit, with no other use. The Ideology DLC significantly expands on the concept, allowing prisoners to be enslaved and forced to work and perform tasks.

Slaves can be created by reducing the will of a prisoner to zero, or by attempting to enslave a prisoner while benefiting from a recruitment inspiration. A prisoner's starting will is usually much lower than their resistance (which would recruit them as a colonist).

Slaves are controllable pawns, much like a colonist. They have many functional differences but act just the same. Slaves are prone to slave rebellions.

Slaves contribute 75% of the raid points of an equivalent colonist.

A slave will have 85% Global Work Speed - they have no motivation to work as hard. To compensate, they have no need for Recreation, and will have increased mood through expectations.

Slaves are unable to do the Warden, Art, or Research tasks. They are additionally unable to:

Tasks that require a minimum Intellectual skill greater than 0 such as crafting Medicine as slaves are considered to have 0 skill regardless of their actual skill level prior to enslavement. Despite Drug Synthesis Speed scaling with Intellectual they are still capable of doing tasks that use this stat for scaling, albeit slowly.
Request caravans, military aid, or persona core location via comms console
Call royal permitsContent added by the Royalty DLC
Be an ideoligious role

However, slavery overrides all other work exceptions. For example, if a colonist would be unable to do Dumb Labor, enslaving will force them to allow Dumb Labor.

Unlike prisoners, male slaves can fertilize embryos.

Slaves do not have the default expectations of colonists. Instead they have unique expectations with a generally higher mood boost. Slave expectations replace colonist expectations based on what the pawn's expectations would be if they were a colonist based on colony wealth and noble status.

Slaves never insult or social fight with non-slave pawns. They are half as likely to social fight with each other.
Slaves cannot share a double bed with non slaves colonists, even if they are married.
Slaves can share bedrooms with colonists, however the colonists will receive −3 mood for doing so (unless they are in a relationship).

Other colonists will see slavery as either an abhorrent or honorable act, depending on the Slavery precept.