A power of attorney is the written legal right, or power, given to another person (the attorney in fact) to act on your behalf. The extent of this authorization depends on the powers granted to the attorney in fact by the person for whom the attorney in fact is acting. A power of attorney authorization can encompass a broad range of acts or can be limited to one specific act.
The authorization will remain in force until either 1) the death of the grantor, 2) the fulfillment of the act identified in the authorization, or 3) the power is expressly terminated by the grantor. While a power of attorney may exist for an extended period, it should be updated frequently since some institutions like banks, mortgage lenders, hospitals, government entities and many others may not honor them if they are over a year old.