levels of urgency - some may bring a scene to an outright stop, whereas others may indicate that a boundary is being approached. A safeword may be used by the Dominant as well as the Submissive if they feel things have gone too far and are uncomfortable continuing. D/s may be ritualized or freeform. It is usually a negotiated lifestyle, with people discussing their wishes, limits, and needs in order to find commonality. A D/s relationship may be sexual or non-sexual, long- or short-term, and intimate or anonymous. Most adherents search for the essential intensity, trust, and intimacy that are required to make any deep relationship possible. Based on gender (of the dominant or submissive), D/s can be divided into the following sub-types: Female dominance Female submission Male dominance Male submission Terminology BDSM is the sexual practices of bondage and pain / torture , dominant and submissive, as well as sadomasochism. D/s participants often refer to their activity as "play", with an individual play session being called a "scene". In addition to "dominant" and "submissive" a "switch" is a person who can take either role. The dominant and submissive relations pertain to two people who play with psychological, emotional, and/or physical dominance. Most of the time in sexual relationships like this there is some sort of power exchange through their physical interaction. A scene between two switches can involve trading off the dominant and 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" flavor. The term power exchange refers to the empowerment of the dominant by the submissive's surrender to his/ her control. Power exchange is consensual and in reality, it is the submissive that has the underlying control during the relationship exchange. The dominant is attempting to satisfy the submissive's kinks and desires. The terms top and bottom are used as verbs or nouns to describe the physical play of SM but with less of a focus of the "sadist" and "masochist" part of the activity.