Understanding what the Dom/sub dynamic is, how it functions, and how to negotiate around it in your own relationship(s) is key to creating the kinky sex life of your dreams. It is the base layer. It is the fundamental configuration of role play.
BDSM, these dynamics become even more explicit. BDSM stands for bondage, Dominance/Dominant, submissive/submission, and sadomasochism. This is when two or more people engage in consensual power exchange. The sub willingly hands over the power within the scene to the Dominant.