In BDSM, a contract is a written-out agreement between the dominant and submissive partners in a relationship. It can be either formal or informal, and is usually written after much negotiation by the Dom/me and the sub, outlining what structure, guidelines, rules and boundaries to the relationship are agreed upon by the two. This article or section contains information that has not been verified and thus might not be reliable. ... A collar is a common symbol of BDSM. BDSM is a term which describes a number of related patterns of human sexual behavior. ... In human sexual behavior, a dominant is one who enjoys performing any of a variety of BDSM practices upon a submissive; or one who holds a dominant position within a relationship based upon dominance and submission (DS). ... In human sexual behavior, a submissive is one who enjoys having any of a variety of BDSM practices performed upon them by a Dominant; or one who holds a submissive position within a relationship based upon Dominance and submission (Ds or D/s). ...

Because BDSM "contracts" usually place unreasonable or unlawful restrictions on the freedom of one or more participants, they are in general not legally binding.