Individuals who can change between top/dominant and bottom/submissive roles—whether from relationship to relationship or within a given relationship—are known as switches.
The precise definition of roles and self-identification is a common subject of debate within the community.
Explicit sexual activity, such as sexual penetration, may occur within a session, but is not essential.
They further argue that setting a discrete line between "safe" and "not-safe" activities ideologically denies consenting adults the right to evaluate risks vs rewards for themselves; that some adults will be drawn to certain activities regardless of the risk; and that BDSM play—particularly higher-risk play or edgeplay—should be treated with the same regard as extreme sports, with both respect and the demand that practitioners educate themselves and practice the higher-risk activities to decrease risk.
RACK may be seen as focusing primarily upon awareness and informed consent, rather than accepted safe practices. The consent and compliance for a sadomasochistic situation can be granted only by people who can judge the potential results.
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.
Failure to honor a safeword is considered serious misconduct and could even change the sexual consent situation into a crime, depending on the relevant law, since the bottom or top has explicitly revoked his or her consent to any actions that follow the use of the safeword (see Legal status).
The terms "top" and "bottom" are also used: the top is the instigator of an action while the bottom is the receiver of the action.
The two sets of terms are subtly different: for example, someone may choose to act as bottom to another person, for example, by being whipped, purely recreationally, without any implication of being psychologically dominated by them.
Activities and relationships within a BDSM context are often characterized by the participants taking on complementary, but unequal roles; thus, the idea of informed consent of both the partners becomes essential.
The terms "submissive" and "dominant" are often used to distinguish these roles: the dominant partner ("dom") takes psychological control over the submissive ("sub").
Bottom and submissive are widely used for those partner(s) in the relationship or activity who are, respectively, the physically receptive or controlled participants.
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.
Terminology for roles varies widely among the subcultures.