Bdsm is an unusual acronym, because it combines six words into just four letters. It’s short for bondage and discipline, dominance and submission, and sadism and masochism.  Bdsm is a group of three related sets of sexual desires and practices:

• giving or accepting sexualised pain, which can involve beating, or the application of heat or cold, electricity or piercing;
• imposing or accepting restraints and other things likely to produce feelings of helplessness;
• demanding or giving submission, service and sexualised obedience to commands.

Any one of those things is bdsm, though most people involved in bdsm seem to like at least two out of three, or all three. 

Strictly speaking (and in bdsm someone has to speak strictly), you don’t need a single one of these items for bdsm. You just need hands, a tongue and genitals

Another way to describe bdsm is to say that it’s a kind of sensibility. Bdsm includes many experiences and feelings shared by people who don’t consider themselves to be involved in bdsm.

Anyone can have moments of sexual surrender when they lie back, close their eyes and let their lover do whatever they want with them. Many people enjoy the fiercer experience of pushing a lover beyond their control so they are no longer capable of reticence or caution.

Not everyone who sometimes feels that way during sex would say they were into bdsm. What’s specific to bdsm is the way it takes these common desires and sensations and seeks to extend, prolong and intensify them.

Another defining feature of bdsm is the way it gives sexual significance to things that don’t usually carry much sexual weight. Someone who kneels before their lover, forehead pressed to the floor, is aware of the posture they’re in and its meaning. That awareness is sexual.

There’s nothing sexy about kneeling. Until it acquires sexual meaning. Bdsm is very much about assigning and enjoying sexual significance to actions and words

In other contexts there’s not much sexual charge to be had from kneeling. Bdsm involves physical intimacy and physical sensations, sometimes intensely, but it focuses not only on how actions feel but also on what they mean.

To an unusual degree, bdsm pleasure involves something almost abstract: the partners’ awareness of their relationship, and the symbols, gestures and words by which that relationship is expressed.

The practices – I suspect – aren’t as important as that awareness between the partners. Which is why it’s true to say that bdsm is both a form of sex and a form of love.