Consent
From BDSM Wiki
Consent is informed, uncoerced permission for something to happen.
When an activity takes place with the consent of all participants, the activity is said to be consensual.
According to the NCSF, "Consent is... [sic] an informed, voluntary agreement by two or more people to engage in a particular BDSM activity or to enter into a BDSM, D/s or M/s relationship".[1] However, the importance of consent goes beyond BDSM and relationships that incorporate BDSM.