A power of attorney is an agreement between two parties: a principal and an attorney in fact. The attorney in fact need not be an attorney at law (a lawyer). A power of attorney gives the attorney in fact rights to act in the principal's place. Attorneys in fact are fiduciaries of their principals.
Powers of attorney may be general, limited or special. They are usually written documents, although some jurisdictions allow oral power or attorney agreements. Many jurisdictions impose special requirements on their form or substance.
Typically, a power of attorney only remains effective as long as the principal is alive and competent to make decisions. Principals may, however, grant durable powers of attorney that persist after they are no longer able to make their own decisions.
[Last updated in January of 2022 by the Wex Definitions Team]