A "Power of Attorney" is a legal document where one party (the Principal) authorizes another party (the Agent or the Attorney-in-Fact) to act on his or her behalf during an absence. "Durable" means that it is also effective if you become medically incapacitated. This is typically a coma or vegetative state which has been confirmed by your primary care physician.
NOTE: This document does not authorize anyone to make medical or other health care decisions on your behalf. A health care power of attorney (also known as a Proxy or Advance Directive) must be created and executed if desired.