Essentially, a power of attorney is a document given by an individual person (donor) authorising another individual person or persons (attorneys) to act or make decisions on behalf of the donor.
The rules governing powers of attorney and guardianship differ from state to state and you should seek advice as to how powers of attorney operate in your state.
A power of attorney is used whenever these is a concern that a person will be able to make decisions for himself or herself (that is, whether the person will not have legal capacity_. The inability to make decisions may be temporary or permanent. Frequently, the need for a power of attorney increases as a person gets older, but the need may also arise for other reasons, such as disability or even absence from Australia for a given period.