A dom-sub relationship is one of the common ways people who may be into kink and BDSM might opt to engage with another. Dom means dominant, and sub means submissive. The two terms are a description of the two roles that the partners might choose to take on within a romantic or sexual relationship.
Dom-sub relationships can be considered an eroticized and consensual exchange of power. These relationships represent the letters DS in BDSM, an acronym that represents Bondage and Discipline, Dominance and Submission, and Sadism and Masochism. The difference in power between the sub and dom is often signified with small-case and capital letters. The acronym is often written as D/s.
The dom is the one who does things to or acts upon a sub. As stated earlier, this is negotiated and consensual, in the sense that the acts did are within the boundaries of the sub of what they want to experience and also within the boundaries of what the dom wants to do.