Well, that’s not so easy to answer.
I could say, rope play, impact play, dressing up in latex and leather, whips, doms, and dominatrices. It’s true this is the most common description of kink, and quite a valid one, but it’s not all of it…
I can describe for you one kinky life of a kitten and her master. One who dominates her through sheer will and mental control. But that is not even the whole of the relationship between a master and their pet. It might involve more sadism, or more pet play (something which this kitten does not do.)
For now, I will simply say that Kink is play.
If your intimate and sexual life involves play with one or many, than I say, that’s kinky. However you practice and however you play. Not the stupid mind games too many practice in the vanilla world that only hurt those involved, generally non consensually, in the games.
No, this is fun play. Or serious, as it might be, but enjoyable, consensual, and, well, free. Free to be whomever and however one pleases. After that, don’t worry about how kinky you are; if what you do “qualifies” as kink; or if you are experienced enough in your fetishes and interests to be a “true” member of that community. Just have fun.
That is kink in a nutshell.