Top, bottom, switch

The terms top, bottom, and switch are used to describe roles for the duration of a sexual act or they may more broadly denote a psychological, social, or sexual identity, or indicate one's usual preference. The terms top, bottom, and switch are also used in BDSM, with slightly different meanings. In BDSM, a top is the person doing something to someone else, and a bottom is the person receiving that act. In both contexts, the terms top and bottom refer to active and passive roles, not to who is physically on top in a particular sexual act. The older term "versatile" is sometimes used instead of "switch."