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 both contexts, the terms top and bottom refer to dominant or submissive, or 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."
There is considerable controversy about the prevalence of tops and bottoms among male/female and straight/gay populations.
In BDSM, top can mean either a dominant partner in BDSM play (such as flogging, binding, being master, humiliating, and sexual play), or a partner who applies stimulation to another, and who may or may not be dominant.
Topping from the bottom is a related BDSM term, meaning a person simultaneously adopts the role of bottom and dom.
A service top is a person who applies sensation or control to a bottom, but does so at the bottom's explicit instructions.
In BDSM, bottom can mean either a submissive partner in sexual play (such as in being flogged, tied, humiliated, or made to serve), or a partner who receives stimulation from another, and who may or may not be submissive.
A bottom in BDSM does not have to be the receptive partner; for example, a female dominant may command her submissive to penetrate her.
A switch is someone who participates in BDSM activities sometimes as a top and other times as a bottom or (in the case of dominance and submission) sometimes as a dominant and other times as a submissive. This is sometimes referred to as being versatile.
Further information: Dominance and submission
Those who take the superior position in dominance and submission scenes and relationships are called dominants, doms (male) or dommes (female), while those who take the subordinate position are called submissives or subs (male or female). A top filling the dominant role is not necessarily a dominant, and vice versa, and a bottom is not necessarily submissive.
The main difference between a dominant and a top is that the dominant ostensibly does not follow instructions, although they are limited by what the submissive is willing to do. The top may sometimes even be the partner who is following instructions, i.e., they top when, and in the manner, requested by the bottom. Contrast this with the pure dominant, who might give orders to a submissive, or otherwise employ physical or psychological techniques of control, but might instruct the submissive to perform the act on them.
The main difference between a submissive and a bottom is that the submissive ostensibly does not give instructions, although they do set limits on what the dominant can do. A bottom is not necessarily a submissive; they may enjoy intense physical and psychological stimulation but not submit to the person delivering it. Similarly, a submissive might not be a bottom; they may enjoy taking orders from a dominant without receiving any physical stimulation. For bottoms who are not submissive, the bottom is most often the partner who is giving instructions—the top typically tops when, and in the manner, requested by the bottom.
Many distinguish top/bottom from dominant/submissive by seeing top/bottom as an expression of physical power, while dominant/submissive is an expression of psychological power. In many cases, the dominant/submissive relationship involves the dominant party psychologically tearing down and denigrating the submissive (consensually, meeting the submissive's expressed needs and respecting hard limits). In contrast, the top/bottom relationship is more commonly marked by mutual respect and support.
Beginning in the 1970s, in some American contexts, people would identify their interests by wearing a set of keys on the side of their belt or a color-coded handkerchief in their rear pockets. This practice, called flagging, began in the gay male subculture.
Further information: Sadomasochism
The terms sadism and masochism is the giving and receiving of pleasure from acts involving the receipt or infliction of pain or humiliation.