Terminology
D/s participants often refer to their activity as "play", with an individual play session called a "scene". In addition to "dominant" and "submissive", a "switch" is a person who can take either role. A scene between two switches can involve trading off the dominant or submissive roles, possibly several times. In contrast, the terms "top" and "bottom" refer to the active (agent) and passive (patient) roles respectively. In a given scene, there is no requirement that the dominant also be the top, or that the submissive be the bottom, although this is often the case.
The term "vanilla" refers to normative ("non-kinky") sex and relationships, the vanilla world being mainstream society outside of the BDSM subculture. The term comes from vanilla ice cream being considered the "default" flavour and uninteresting.
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