Term referring to where a party is formally made the slave to another, in a total power exchange situation.
A ceremony in which there are witnessed, and a binding detailed legal agreement is agreed upon, in where one party agrees to hand over complete control over their life, to another, as being their slave.
This is a formal agreement, similar to any wedding, or other commitment ceremony, but with far more specific details agreed upon, prior to the formalization ceremony.
In some instances, in place of rings, a collar is placed around the 'slaves' neck, to signify their ownership to the other party.
Noteworthy: There can be three stages of 'collaring'. While not formal it is generally followed among many in the BDSM community.
The first stage is where the submissive can, at anytime, remove the collar, ending the relationship without any hard feelings. Referred to as the 'Collar of Consideration'
Second stage is akin to an engagement ring, and is noted as the 'Training Collar'. This helps to signify a growing attachment between the parties.
Similar to an 'engagement ring' in normal or more straight laced relationships.
The third state is referred to as the 'Slave Collar' in which the relationship is formally agreed to, and entered into. Similar to a wedding band.
In some circles, this final stage is also noted as being more permanent, than a wedding ring or band. While there are exceptions in where a person can have their collar removed, it generally signifies a failure on both parts, and is a stigma that used to apply to divorces.