A document in which you name a person or persons who can conduct financial transactions for you. The person you name is authorized to sign for you and conduct any business that you would be able to conduct, if you were present. If you wish to limit your Agent's power, you can restrict it in the document. A "Durable" Power of Attorney for Property is one that is valid even if you become incompetent or incapacitated. There is specific language in the document that makes a Power of Attorney "durable". If you do not want someone to be able to act for you if you are incompetent, the specific language should be excluded from the document. In most cases for estate planning purposes, a Durable Power of Attorney is used.
Revocable Living Trust
A Revocable Living Trust is a tool used to eliminate the probate process at your death, by creating a Trust and transferring your assets into it. Since a Trust doesn't die when you die, any assets in the Trust do not have to go through probate. While you are alive, the assets are handled just like they would be if you owned them in your own name. Since you name yourself as the Trustee and the beneficiary of the Trust, as long as you are alive you have full control of your assets just as you do now. The Trust is revocable, so you can change it or eliminate it and put the assets back in your name individually at any time.
Will
Formally called your "Last Will and Testament", your Will is a statement of what should be done with all property owned by you at your death. A Will does not eliminate the need for probate as many people mistakenly believe, but it is the document giving direction to the probate court as to how your assets should be distributed. It controls all property in your name and not passed to your beneficiaries by Joint Tenancy, "pay on death" clauses, or direct beneficiary designations such as you would find with a life insurance policy.