One of the core principles of BDSM as paired with Bondage. The 'D' in BDSM stands for Discipline as well as Dominance.

A form of role play where the participants agree on rules and are abiding by these rules. If rules are broken the person being the Top-type role will Discipline the Bottom-type role. The Discipline may come in the form of physical or mental punishment and may range from Impact Play to not allowing the Bottom role to have an orgasm.

Generally speaking the punishment is not the thing that is desired, it is the constant reminder of structure and rules that is the central aim of this kind of play.