This authority can be granted willingly, (as in the case of someone who cannot attend a meeting sending another to vote in her place) or unwillingly (such as in the case of a parent's authority over the affairs of a child. It can be granted with or without limitation ("Go to the meeting and vote yes on the takeover, for all my shares." or "The Executor is granted any and all reasonable powers necesary to manage and maintain the estate of Jonh, while he is in his coma.")
A parent, for instance, holds an automatic right of proxy in certain interests of her child. The child need not and cannot make decisions not granted her by her parent, because the parent has the legal authority to make those decisions for the child.
When something is done or decided by proxy, it means the actual effort of action, and sometimes the decision, was made by someone else.
But dosent a dog have the cleanest mouth in town? "maybe, but all i know is that they have the cleanest balls and asshole in town
Guy: Yeah, dude you're so funny.
Byproxy: "Respect my authorit-ii!"