The National Coalition for Sexual Freedom's community glossary defines a top as the doer or facilitator of an action and a bottom as its receiver. In impact play, the top uses the hand or tool. In rope, the rigger or rope top applies the rope. The activity tells you what topping means in that sentence.

A bottom may be struck, tied, touched, penetrated, teased, restrained, photographed, or placed in a sensation-focused position. Receiving the activity does not reveal who requested it, who chose the details, or who has authority.

Usage has never been perfectly uniform. An Encyclopedia of Sex and Gender history of top and bottom traces the words through gay leather, BDSM, and sexual-position contexts, where action and power sometimes travelled together. In present-day conversation, name the activity if the meaning is unclear.

A dominant holds authority over a defined part of an interaction. A submissive follows that authority within its scope. Commands, service, permissions, rules, ritual, and controlled choices can create the exchange even when no physical activity has a clear giver and receiver.

A study of 33 people in 17 long-term BDSM relationships makes the distinction concrete. Its authors describe a dominant ordering a submissive to flog them. The dominant bottoms because they receive the flogging, while the submissive tops because they perform it. Authority stays with the person directing the action.

Dom is a common short form of dominant, and sub is a common short form of submissive. The label alone does not say whether authority lasts for one scene, appears only during sex, or extends into parts of a relationship.

In this pairing, the dominant directs the scene and performs the activity. The submissive follows and receives it. A dominant top might order a position and then apply rope, impact, touch, or another sensation.

People often shorten this combination to dom and sub because the action roles match the power roles. Even here, the submissive bottom may move, speak, perform a task, or ask for an experience. Bottom does not mean inert, and submissive does not mean without preferences.

A dominant bottom receives an activity while retaining authority. They may instruct a partner how to tie, touch, penetrate, spank, worship, or serve them. The dominant can choose the activity, pace, sequence, and meaning while physically receiving it.

A submissive top performs the activity under direction or as service. They may massage a dominant, apply a requested sensation, tie them according to orders, or carry out a sexual act chosen by the dominant. Top describes what they are doing, while submissive describes why authority rests elsewhere.

Do not assign the power role by posture, clothing, who holds the tool, or who appears busiest. Ask who directs and who follows. A person standing over a partner may be the submissive top; the person lying down may be the dominant bottom.

A service top performs an activity to provide the receiver's desired experience. The bottom may specify sensation, pace, position, or technique. The service top might be submissive, but service topping can also be role-neutral. The term does not settle the power question by itself.

Role-neutral partners can trade activities as peers. Rope partners might alternate who ties for practice. Impact partners might take turns because both enjoy giving and receiving sensation. Sexual partners also use top and bottom without any BDSM hierarchy.

Switch can name flexibility on either axis. The relationship study above uses switch for people who both top and bottom, while Bennett's interviews with 15 Australian BDSM switches discuss movement between dominant-type and submissive-type roles. Say power switch, top/bottom switch, rope switch, or impact switch when the distinction matters.

Use top and bottom to answer who performs and receives an activity. Use dominant and submissive to answer who directs and follows. Use both when both facts matter: dominant bottom, submissive top, dominant top, or submissive bottom.

Add the activity because the answer can change. 'I bottom for rope and top for impact, with no D/s role' is precise. So is 'I am dominant with this partner and sometimes bottom when I want them to provide a sensation.'

The Dom, Sub, or Switch Test compares broad power positions. The Rope Role Quiz compares tying, being tied, and rope switching. Neither test decides the other axis.