What is a Power of Attorney?
In a Power of Attorney, you ("the principal") name a chosen "agent" to exercise legal authority on your behalf the same as if you were doing it yourself. The authority granted can be whatever rights you desire the agent to exercise over your legal affairs and your property. Such authority can include making deposits and withdrawals from your bank accounts, managing your investments, selling your home or anything else you could do yourself.
Typically such Powers of Attorney in an Estate Plan take legal effect immediately. Also, the legal authority granted the agent in all Powers of Attorney terminates at the principal's death and usually also terminates if the principal becomes mentally disabled.