What is the origin of the idiom "come to heel" and when to use it?

The idiom "come to heel" originates from dog training and the practice of teaching dogs to walk obediently by their owner's side. In dog training, the "heel" position refers to the dog walking close to the handler's left leg, with the handler's left hand holding the leash. The command "come to heel" is used to instruct the dog to return to this position. It can be used in personal relationships, such as a parent instructing a child to "come to heel" to reinforce discipline or obedience.