In a more casual context, the act of being collared can also be used in light bondage or role playing.
More About Collared
There are several types of collars that can be used, but they do not necessarily represent a permanent D/s relationship. The collar of protection, for example, is a symbol to show that a submissive without a permanent Dominant is under the protection and watch of a Dominant that he or she knows. They may or may not engage in play sessions together. This form of collaring is often applied to individuals who have suffered some form of trauma and would like to feel safe.
A training collar often occurs after several discussions about the needs, desires, conditions, dislikes, likes, soft and hard limits, and the rules established by both parties.
A permanent collar represents the fact that the submissive and the Dominant have reached a fully-established relationship which they hope will last for life.