The resulting consent and understanding is occasionally summarized in a written "contract", which is an agreement of what can and cannot take place.Use of the agreed safeword (or occasionally a "safe symbol" such as dropping a ball or ringing a bell, especially when speech is restricted) is seen by some as an explicit withdrawal of consent.The interaction between tops and bottoms—where physical or mental control of the bottom is surrendered to the top—is sometimes known as "power exchange", whether in the context of an encounter or a relationship.
Explicit sexual activity, such as sexual penetration, may occur within a session, but is not essential.
There are distinct subcultures under this umbrella term.
Terminology for roles varies widely among the subcultures.
Such explicit sexual interaction is, for legal reasons, seen only rarely in public play spaces, and it is sometimes specifically banned by the rules of a party or playspace.
Whether it is a public "playspace"—ranging from a party at an established community dungeon to a hosted play "zone" at a nightclub or social event—the parameters of allowance can vary.