Exactly as it says in the title. There is a misconception of what CNC is, that's r*** play or fantasies, that it's highly controversial, etc. Well it's not, it shouldn't be, and I'm here to explain what CNC is and what it actually means.
Let me preface this by first addressing r*** play: r*** play is not real. Play is consensual, else it is no longer play and is r***. Consent is not some absolute binding agreement to do what you want without the other person being able to do anything about it. Consent is also not something that is given at the start and cannot be rescinded later. Consent is fluid: it can be given at one moment and rescinded the next. When you take away someone's power to rescind their consent, that's assault. Someone choosing to not rescind their consent is different from someone who did not have the choice.
What people often mistake for their r*** play fantasies is actually CNC, except it's not r*** because you have you power to consent and rescind consent at all times. CNC, consensual non-consent, is the idea of giving implied consent, that is it prior consent you give your dom to *initiate* a scene without prior notice. The key here is that the scene can only be initiated. You may be surprised by the start of a scene, but you always have power to revoke your consent during it. If you say stop, it stops.That is the essence of CNC.
Some examples I've heard/done are surprising your mate as they walk through a doorway, tying someone up in their sleep, ambushing/overpowering your mate, etc. You can even get into more extreme means like extending the CNC play to outside the home (establishing kidnapping scenes), permission to do things while your partner is asleep/non conscious and thereby not able to give consent but gave it prior, or a bidirectional play dynamic with CNC such as primal play. What's important here is two proponents: first is that consent to initiate a scene was given prior to the scene being initiated, and the second being consent to that scene has not been revoked during that scene.
So you see it isn't r*** play because you always have consent in the situation. You always have power to rescind consent and stop the scene. What CNC aims to do is provide more spontaneous playstyle that better mimics how domination would happen in a real life scenario. Furthermore, I personally do not believe in r*** play because if you want it to stop and you can't stop it, that is no longer play to me. Play is your consent to engage in bdsm activities willingly. And as such, I would say no one should ever engage in "r*** play." Do CNC instead and keep your power to not consent.
And I understand that some people want that feeling where they don't have the control and can't do anything about it, but at a certain point, the fantasies need to be dialed back so play can stay safe. You don't have to use your out if you don't want to, you can even pretend it's not there outside of an emergency, but having that choice to stop is what makes it consensual play.
But also do not just jump into scene with someone who says they're into CNC. CNC takes a firm understanding of what it means to consent, and many people do not have that. I look to certain laws that tried to say you could not rescind consent to sex after starting as examples that people not only do not understand the full picture of consent but are also not educated to. As always, it comes down to whether you can trust your play partner to respect you when you want to stop, pause, talk, not do something, etc and especially so when you are made vulnerable around them. And of course for some people just the initiation alone can be enough to trigger a traumatic episode, so CNC is definitely not for everyone, but I'm sure you know your relationship and partner(s) well enough to decide whether it'd be worth exploring or not
Play safe, and I hope this has helped to clear up some of the misconceptions around consent and CNC