Cuffing is the informal term used to describe the process by which a human is able to control an angel or demon
Angels are cuffed using either bronze or silver. The interior of the cuff is inscribed by the name of God, and swears the angels allegiance to the owner. The front of the cuff is usually inlaid with the crest of the owner and sometimes their name.
Low level angels are easily restrained by such measures, but some higher level angels, are able to resist some measures put in place by the cuff, but not others. For example, Gabriel is able to resist instructions but cannot escape the 'stop' command.
Demons are cuffed by gold. The exterior of the cuff is encrusted by Dead Sea Salt and the interior is engraved with an incantations, which works in the same way a contract would. Owners of demons generally will also have the demon tattooed with their crest as a form of identification. Sometimes, to prevent any potential disasters, demons will be tattooed with a second incantation making it impossible for them to ever harm their owners, past or present.
Demons of a high calibre are often able to temperarily fight of the physical cuffs powers, but none have so far been able to resist the tattoed incantations.