In a BDSM context, a collar is a device of any material worn by a person around the neck to indicate their submissive or slave status in a BDSM relationship. A person wearing a collar to symbolize their relationship with another is said to be collared. Some people conduct formal “collaring ceremonies,” which are regarded as effectively solemnizing their relationship in a similar way as a marriage ceremony and the collar having similar significance as a wedding ring. The standard form of a collar is a black leather band around the neck, often with metal D-rings added to allow the attachment of a leash, rope or other restraints; but to be more discreet in public, some people may wear an ordinary choker or jewelry necklace for the same symbolic purpose.
Collars may be used in role-playing games involving erotic humiliation because they have connotations of control and pet-like status, especially when worn with a leash.