This is a document where you name a person to speak for you, if you are incapacitated or cannot make your own decisions for some other reason.  The person you authorize to speak for you is your Agent in the power of attorney.  Your Agent can step into your shoes and make all of the decisions that you normally make.  Of course, if you want to limit your Agent’s decision making authority, then you simply put that information into your power of attorney.  A power of attorney can only be used when you are alive.