The fundamental principles for the exercise of BDSM require that it should be performed with the informed consent of all involved parties.
Since the 1980s, many practitioners and organizations have adopted the motto (originally from the statement of purpose of GMSMA—a gay SM activist organization) "safe, sane and consensual", commonly abbreviated as "SSC", which means that everything is based on safe activities, that all participants be of sufficiently sound/sane mind to consent, and that all participants do consent.
Given the wide range of practices, some of which may be engaged in by people who do not consider themselves as practicing BDSM, inclusion in the BDSM community or subculture is usually dependent upon self-identification and shared experience.
and is interpreted as a combination of the abbreviations B/D (Bondage and Discipline), D/s (Dominance and submission), and S/M (Sadism and Masochism).
Some BDSM practitioners prefer a code of behavior that differs from "SSC" and is described as "risk-aware consensual kink" (RACK), indicating a preference for a style in which the individual responsibility of the involved parties is emphasized more strongly, with each participant being responsible for his or her own well-being.
Advocates of RACK argue that SSC can hamper discussion of risk because no activity is truly "safe", and that discussion of even low-risk possibilities is necessary for truly informed consent.
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).For their consent, they must have relevant information (extent to which the scene will go, potential risks, if a safeword will be used, what that is, and so on) at hand and the necessary mental capacity to judge.The resulting consent and understanding is occasionally summarized in a written "contract", which is an agreement of what can and cannot take place.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").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.